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Messages - Da_Stier

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1
Thanks, Christian!

These are some very interesting rabbit holes topics to look into.
I like the microchip unit (the TimeLab one) however I almost fell off my chair when I found the pricing. (22k€ for the base unit).
On the other hand the TinyPFA for example looks like a very interesting thing for further reading, a nanoVNA is certainly cheap enough to give it a try.

One (maybe very naive) question I still have is the following:
Starting from a very basic frequency counter architecture like the one found in the 2021 edition of the ARRL handbook, what limits the actual resolution?



With a 1s gate time you get a 1Hz resolution.
With a 10s gate time you get a 0.1Hz resolution.
What would stop me to get a 0.01Hz resolution with a 100s gate time?
With this logic I should get down to 1mHz at a 1000s gate time, for a long term measurement, a roughly 17 minute gate time would be ok for me.
Assuming my reference is known good, I should atleast be able to measure the long therm stability of my testsignal, right?




Now for the update on my units.
I just finished all 48 "production" units.
This finally allowed me to get rid of the chaos in my bedroom and get to a nice box of finished units.





From the 50 PCBs I got assembled, I had 5 with some sort of failure.
These were the following:
- solder bridge on the USB C connector -> easy fix, works now
- unsoldered pin on the USB C connector -> easy fix, works now
- unsoldered pin on the QFN -> easy fix, works now
- 13MHz OCXO instead of a 10MHz one -> error on my side, easy to fix, works now
- some error on the 3V3 LDO -> board literally went up in flames, got scrapped

This was some very interesting information to get a feel for what fails at what rate.





Greetings,
Michael

2
Thanks Mads.  :)
Yeah, I know, night-me got tired at last so it is slowly getting better.

I took a look at the GPS clock you have, seems like a really nice unit.
I think a permanent antenna and a little rack together with a distribution amplifier would make a great setup for your gear.
(Also a video about such a setup would be pretty cool)



I had one of my sample units running 24/7 for a little over a month now.
I fed a 10MHz output into a frequency counter with a known good GPSDO delivering the counters reference.
The maximum deviation between the two was 1 count on my counter.
This equals 0.1Hz or 0.01ppm or 10ppb.
This seems reasonable I think, however I don't like how I only got a single count to go by.
I know that I can look at the phase on a scope and measure the time it takes for the phase to do one period for calculating very small differences in frequency.
However it seems like there should be some frequency counter with mHz resolution out there, right?
Does anyone know about such a device?
All counters I came across until now, have 0.1Hz as the minimum resolution at a 10s gate time.

Other then that, I finished the tooling.
It turned out to be a combination of 3d printed parts and aluminium parts.
It uses some linear bearings on 8mm steel rods to provide a smooth operation.





I made some magnetic inserts with 2 guiding pins for alignment.
One that holds the bare PCB and one for the complete unit to have simple "drop in and push closed" operation.

The contactpoints for the SMA outputs are a combination of pogo pins with GND shrouds and SMA connectors without the nut.
It turns out the U.FL to SMA pigtails have slightly recessed inner conctacts so I needed to schange to top row over to the SMA connector style.



For multiplexing the signals to an oscilloscope, I used the RF switchmatrix, I made a while back.
Pretty overkill for the 10MHz testsignals but I already had it ready.



The tooling turns out to be an absolute life saver while going through all 50 units.





Greetings,
Michael

3
General Chat / Re: Best Solution for a 80MHz / 100kV Source
« on: February 26, 2024, 07:06:24 PM »
If you need a continious supply, might it be possible to use a solid state UKW FM radio amplifier and an impedance matching network?
Solid state amplifiers like this easily reach several kW and if you match the 50 ohm output to a high impedance, the voltage will go up significantly.

I don't know how commercial accelerators do it but I have seen giant arrays of solid state RF amps at places like the LHC before.

A quick calculation to see where you would end up with:
V = sqrt(P*R)
V = sqrt(2000W * 50Ohm) = 316V
If matched to for example a 10kOhm structure (no idea what impedance your accelerator structure would actually have)
V = sqrt(20000W * 10*10^3Ohm) = 4472V

Far away from 100kV but wouldn't the impedance of the structure define the voltage anyway in order to actually dissipate the 2kW?

4
So at this point, both Gregory and I had some ideas on what to improve, how to get better firmware going and also on what to get out of the project.
So once again "night me" opened KICAD and worked on the next iteration.
By far the most motivating reason for this was, that Gregory suprised me by completely rewriting the firmware and making it way more responsive and overall way better.
So while being at it I decided this would be a perfect opportunity to see how a project like this would scale up.

And while "day me" was still a little unimpressed by the thought to go all out and build a lot of these references, "night me" was collecting quotes from manufactures and working on a breakout box for testing.
This breakout box made it really easy to work with the device, since it drastically reduced the amount of wires and other clutter needed on the desk.
It has LEDs on all the outputs, switches on all the inputs and banana jacks for everything else.





This picture also gives a preview on the next change, I got some screenprinted enclosures, custom made for me by Hammond.
Their service was really helpful and it was pretty easy to get them printed.
.... and still cheaper then the standard  version off of Digikey.   :o
I don't think I mentioned this before but the endplates for the enclosures are actually aluminium PCBs.
I found this to be by far the cheapest way to get CNC milled, black lids with custom screenprinting on them.

So what was the plan from here ... make 50 units of course.
This is when the real work began, I got myself 50 boards of version V1.1.
Why? To learn how to scale things up, to see, what works and what doesn't if you have to do it 50 times.
Also to see what is important for getting boards populated.
I guess I'm in a rather lucky position here, since the company I work for actually has a PCB assembly line.
This meant that I was the one populating these boards, which meant I had all the possibilities to learn from it.



And while 50 pieces didn't sound too bad at first, I quickly realized, how much 50 actually is.





So the very first thing I learned is to reduce manual work as much as possible.
I think I did a good job by getting all the lids professionally made, by using SMA pigtails that just need to get plugged in, etc.
However some other parts, like having no mechanical index for the edge launch SMA connectors for example, turned out to be a timely oversight.

On the software side of things, Gregory did an outstanding job by implementing a Web UI on the ESP.
This means that you can either configure the device via the CLI and forget it or to have a live Web UI to change all the settings.
This expanded the use case of the unit from a "dumb" reference to an actual signal generator for lab use.



This also meant that I got a lot of new ideas on where to go from here.
For example I implemented a proof of concept IQ function to have up to two IQ channels, providing signals at 90° phase offset.

So where am I at right now?
The 50 units are built up but not yet calibrated or tested.
After thinking about how to do that, I decided on building a teststand for the unit.
This makes testing a lot easier, since it saves me from connecting and disconnecting a million SMA connectors.
I came up with a "quick connector" consisting of an aluminium shround and a pogo pin.
The goal being to have a "drop in a board and push it closed" kind of device.



So that's basically it for now, I will keep posting updates as soon as I got some more work done.
Also, if anyone is interested in getting a reference like this, feel free to contact me, I have a few.  ;)



Greetings,
Michael

5
Hi all,

long time no see. I spent the better part of the last year on developing an OCXO based frequency reference.
Since it got a little out of hand and I learned a lot in the process, I thought why not tell the story here.

Let's start from the beginning. Last year I had some trouble sleeping so at one point I decided to make the best of it and let "night me" develop something instead of staring at the dark ceiling.
After thinking a bit I decided to tackle a problem that I had for a while now.
My QO-100 HAM radio station needs several reference frequencies - one at 25MHz for the LNB and one at 40MHz for the SDR transceiver I use. They also need to have different amplitues and can't have a lot of jitter.
My old setup used a dual channel GPSDO, made by Leo Bodnar - which is a great device - but I didn't like the dependence on a GPS signal.
I had trouble before with not being able to operate due to the setup being under a roof of some sort.

I previously tried to use two of my little PT7C4511 breakouts to sync everything to a common 10MHz source.
As the source I came up with a very simple OCXO brekout with an integrated 6dB divider.





While it looked promising on the oscilloscope, it turns out, that there is way to much jitter on the outputs to be of any use.
This caused me quite a bit of confusion first, since I couldn't figure out, why nothing would lock on to these signals, unitl I realized the horrible jitter.

Next I remembered the SI5351 IC that is very commonly used for all kinds of reference purposes, from both hobbyists as well as in actual commercial products.
The most common one that can be found on a lot of cheap chinese breakout modules is the SI5351A which is the 3 output version that runs off of a external chrystal.
These modules look like this:



These are pretty nice and can basically do what I want, however I didn't like the 3 channel limit or the clock source being a chrystal at some random frequency.
After looking at the datasheet, I realized, that there is a SI5351C version available, that offers up to 8 outputs and can run from an external single ended input.

PERFECT.  :)



These chips are controlled via a simple I²C interface, run off a single 3V3 supply and need almost no external components.
So I got myself a few of them on Digikey and build a little breakout board.
Since I didn't want to wait for PCBs to arrive, I decided on a deadbug breakout, which is a nice challenge in itself, considering the 4x4mm 20 pin QFN package.



I reused the OCXO board from earlier and built a first mockup of the basic system I wanted to create.



I found a great arduino library to control the SI5351 series of ICs by NT7S.
If anyone is interested, it can be found here:
https://github.com/etherkit/Si5351Arduino

As a controller I chose to use an ESP32, since it runs at 3V3, is pretty cheap and easy to assemble.
After getting the proof of concept version going, I started to work on an actual board.
I wanted it to be a rather clean looking unit and decided to use a Hammond enclosure, since I used them before and they are affordable.

So after a couple of nights, "night me" came up with the first design, orderd all the parts for a few prototypes and a couple of weeks later, "day me" received everything and started the assembly.
This is what the first board looked like:



It also fitted nicely into its enclosure.





For software devlopment and debuggind, I like to make a "sceleton version" of the enclosure.
This offers access to all the LEDs, measurement points, etc., while making sure that it will stay at the final formfactor.





After this came  A LOT of firmware nights to get all the features going, that I wanted.
This includes:
- serial terminal via USB connection with a command line interface for setup
- saving all settings to memory
- recalling all the settings on startup
- two LEDs for status
- setting all eight channels in frequency and amplitude
- an external 10MHz input / output, depending on the mode it works in

It didn't take long for the first issue to come up.
During the hardware design I planned to use a dedicated programmer to flash the ESP.
This worked fine but by then I preferred to flash it via the same USB that is used for the CLI (command line interface).
Therefore I did my first mod on the protoype units and added a small auto reset addon.



With this mod I was now able to flash it via USB - much more comfortable.
By then I got most of the firmware going, the code looked horrible but it worked.
At this point I sent one of the units to Gregory - a friend of mine, over in Brazil.

He runs a youtube channel and did a review / gave some comments on one of my prototypes.


I also attached one of the units to my QO-100 setup and it worked the first try.  :D
This was a great success for me, especially since all of this came out of boredom basically.
The unit attaches nicely to the tripod I use for the satellite dish and I am finally independent of any third party signal - except the satellite of course.




At this point I thought I am done with this project, I built 5 prototypes, with one being in Brazil ... but it turned out, I was far from done.
I will split up the post here to make it a bit easier to type out.


6
I came across a whole crate of these exact boards on the scrapyard, some time ago. I guess now I know where they came from.
The combination of the old TV network stuff going only in one direction and the fibre seems pretty interesting, I wonder how much of it was an afterthought that just got "bodged on top" and how much was actually meant to be added at some point.

These cases are pretty cool, I think they make great project boxes, maybe even for stuff that gets mounted outside or on a antenna tower or something similar.

As always thanks for the look.  :)



Greetings,
Michael

7
Radio Frequency / Re: Rohde & Schwarz 100W UKW FM broadcast amplifier
« on: August 19, 2023, 01:42:55 PM »
Thanks Mads,

as you say, it isn't always about knowing every bit of circuitry and every value but much more about understanding how to get it going or exploiting it.  ;)

I think the biasing is mainly a band thing. Most lower frequency stuff (like shortwave and maybe up to 70MHZ) I have seen uses bipolar devices and the techniques common for them. This means a simple big bias resistor, maybe some feedback resistor to get a flatter respone over a wider bandwith and often even a diode simply glued to the power transistor to help with thermal stability. This carries over to more modern MOS devices as well, I guess the designers just stay true to the stuff that worked in the past.

On the other hand most microwave amplifiers (in the GHz range) can't really do this and use a Lambda/4 transmission line to apply the gate bias. Since the DC end has capacitors on it which are a RF short, the gate of the LDMOS sees it as an open, minimizing the effect on your cirucuit.

The FM broadcast band is kind of in between the frequencies that can still use the "crude" stuff when done right and needing the microwave treetment. So I guess it depends on the engineer developing a circuit, which technique will be used.



Greetings,
Michael




8
Radio Frequency / Rohde & Schwarz 100W UKW FM broadcast amplifier
« on: August 05, 2023, 01:25:16 PM »
Hi all,

I recently got a 100W FM broadcast amplifier module from Rohde & Schwarz.
I didn't get any documentation with it and the internet doesn't seem to know about this module at all after a quick search.

So I thought, it might be interesting to show the module and what I had to do to get it going.
This is the complete module, as I got it:



It has a quite large heatsink / cooling channel piece attached with two 60mm fans providing airflow.



Now for the "reverse engineering" or in this case either a chain of measurements and tests to see how it works.
I figured out that the power connector with 3 positive and 3 negative wires connects directly to the drain / collector of the main output device. (I didn't know yet what technology it uses but by the looks of it, it might be bipolar). Also it ONLY connects to that.



The big resistors going over the device are more common on BJT devices so to see what I dealt with, I desoldered them to take a look at the device.
Surprisingly it was a BLF278 (a very common VHF power transistor) which is a MOS device.
I didn't think too much about the exact circuit yet but the big resistors might actually be a rather crude way of biasing it.



This information is very important, since it tells me which voltage I need to apply.
BJTs run mostly on 13V, while MOS or LDMOS devices run on either 27V or 50V.
This one is a 50V transistor but it will work fine with 48V as well.

The driver is a BGY33, with the BGY series being a very common 20W power module which is available for different frequencies / bands.
These modules are made to run directly from 12V without any external biasing which makes them easy to use.
I traced back one of the 12V lines to a supply rail which is interestingly supplied via an IDC ribbon cable connector.



The second 12V supply of the driver module is switched by some logic.
Since I didn't feel like getting through all of that and building my own controller, I just traced it back enough to see how it is switched.
It is switched by a small BJT, which means that I can just backfeed the 12V into it.

So I added a small bodgewire to get the driver going.



I also attached a 12V supply wire since I didn't feel like making a ribbon cable for it.
Since the case has a hole pattern on the sides, it makes it easy to run the wire out of the unit without any modifications.



And that was about it, just like this the amplifier was amplifying once again.
With 5,5dBm of input power @100MHz, it produces a very stable 105W on the output.



To do so, it uses 2.57A @ 12V and 6.5A @ 48V, meaning it uses a total of 342.8W.
This gives it an efficiency of around 30%, which is about what I would expect.

By driving it with 13dBm on the input (and saturating it), it produces about 230W and is propably well into class AB or maybe even class C, since the efficiency goes up to right around 50%.



Greetings,
Michael

9
General Chat / Re: PCB Test point, probe insert
« on: July 08, 2023, 01:16:34 PM »
These are still available at digikey.
However I wouldn't want to find fitting probes for them.
Also they are quite expensive so you propably don't want to use them in any considerable amount.

https://www.digikey.de/de/products/detail/cinch-connectivity-solutions-johnson/129-0701-202/241112

https://www.digikey.de/de/products/detail/cinch-connectivity-solutions-johnson/129-0701-301/35164

https://www.digikey.de/de/products/detail/cinch-connectivity-solutions-johnson/129-0701-302/241113




Greetings,
Michael


10
Hi Coupling,

yeah the Verilog VHDL debate is a never ending one.
I think Verilog is mostly used in the USA and some parts of Asia while VHDL is dominant in Europe.
I don't think it really matters which one you learn after all.

I checked out one of my old projects in Quartus II 17.0 real quick to show you the state machine viewer :








Greetings,
Michael

11
Hi Coupling,

you might also want to take a look at the state machine viewer of Quartus if you didn't already.
It can help to identify "wrong turns" or incomplete / overdefines junctions, that the synthesizer might still be able to get going.

I always tend to include a watchdog / timeout logic in each state of my state machines so that there is always a forced way to a safe state in case of a problem.

Other than that, I can also add to what SteveN87 already said, try to include a line for each IO / clock / tightly defined line in your sdc file, it really helps to let the synthesizer know what to look out for.

I might be able to look at your code, I have Quartus II 13.something and 17.something installed.
However I only "speak" VHDL and don't have a clue about Verilog.


Greetings,
Michael

12
Hi all,

sorry for not giving any updates lately, I was pretty busy.
I managed to get hold of a BBU3900, which is Huaweis baseband unit that is compatible with quite a few of their remote radio heads.
It also is pretty modern and while I'm not a 100% certain, that they still sell this exact model, it is still in use in a lot of cellsites.

The unit is a single 2U 19" rackmount enclosure, that takes plugin cards to configure it the way you want / need it for the cellsite.
This is the outside view of the complete unit:







There is a very interesting thread on the Huawei support forum, that shows the purpose of each of the cards.
You can check it out right there, if you want to:
https://forum.huawei.com/enterprise/en/an-anatomy-of-huawei-bbu3900/thread/873125-100305

These are the cards that I got:

GTMU:

Functions (taken from the Huawei link)
1- Controls and manages the base station
2- Supports fault management system, configuration management system, performance
management system, and security management system
3- Monitors the fans and power modules
4- Provides and manages the clock source of the base station in centralized mode
5- Provides the clock output for test
6- Provides the ETH port for maintenance on the OM system
7- Supports transmission through four E1s
8- Provides CPRI ports for communication between the BBU and the RFUs
9- The GTMUb supports interconnected BBUs.
10- Four IDX2 ports on the backplane of the GTMUb can achieve the function of baseband

resource pool backup.










UMPT: ( Universal Main Processing and Transmission)

Function (taken from the Huawei link)
1- Monitors Performance
2- Signals Processors
3- it has A USB flash drive can be inserted into the port for software upgrade and basestation commissioning.
4-The GPS port on the UMPTa6 orUMPTb2 is used for transmitting radio frequency(RF) signals received from the antenna to the satellite card.
5-  It Performs OM (Operation and Maintenance) functions. Further it also do configuration management, equipment management, performance monitoring, signaling processing, and active/standby switch over.
6- It Provides clock reference,transmission ports,and the maintenance link connecting to the OMC. Here, OMC can be the LMT or M2000 client.








UBBP: (universal baseband processing unit)

Functions: (taken from the Huawei link)
1-  Multiplexes baseband resources among different modes, thereby supporting multimode concurrency.
2- Provides CPRI ports for communication with RF modules and processes uplink and downlink baseband signals.








UPEU: (Universal Power and Environment Interface Unit)

Functions: (taken from the Huawei link)
The Universal Power and Environment Interface Unit (UPEU) is a mandatory board
of the BBU3900. It converts -48 V or +24 V DC power to +12 V DC power. The
UPEU is classified into the Universal Power and Environment Interface Unit Type
A(UPEUA) and the Universal Power and Environment Interface Unit Type B
(UPEUB). The UPEUA converts -48 V DC to +12 V DC and the UPEUB converts +24 V
DC to +12 V DC.

1- Converts -48 V or +24 V DC to +12 V DC that is applicable to the boards
2- Provides four ports with two ports transmitting two RS485 inputs and the other
two ports transmitting eight Boolean signals
3- Provides reverse connection protection for power cable connectors.









Interestingly Huawei uses the same power and data connector on this Power supply module as they use on their RF power amplifier pallets.


I also managed to get a copy of all the manuals (the installation manual, the setup guide, both for hard- and software, etc.)
I also thought that I found a copy of the configuration software, called "Site Maintenance Terminal System", however it turned out to be a loose end.
So currently I got the whole system - atleast hardware wise - but miss the software to set it up.
I will still be looking, maybe I can get my hands on the software at some point but without it, it looks like this is about it.
.... on the other hand it is a good thing that the software controlling infrastructure isn't just available to everyone, I guess.


Greetings,
Michael

13
Transformer (Iron Core) / Re: Welding a MOT
« on: January 25, 2023, 10:21:43 PM »
As far as I'm aware it shouldn't really matter, it would work the same even if you had two completely different cores.
The only thing is that it might rattle a bit if one piece is loose.
In that case some glue should fix that.

Greetings,
Michael

14
Electronic Circuits / Re: Ericsson RBS 6601 RRUS 12 analysis(kind of)
« on: November 22, 2022, 08:22:09 PM »
Hi and welcome to the forum  :)

Here are some of my thoughts on your points:

1. You want to be able to detect very small changes in VSWR and expect it to be in a somewhat reasonable range (like 2 max.).
If you have a VSWR close to 1 I could imagine that the amplifiers are used to get the reflected signal into the dynamic range of whatever they use to monitor it.
Another possibility would be the actual monitoring of the signal. A lot of RRUs have a complete IQ receiving path at the diplexer output to be able to set all the preemphesis etc. to get a good signal.
This is also kind of important on another question you asked about the feedback for setting the operating point of the PA.

2. There are quite a few DACs in these things doing all kind of calibration, preemphesis, operation point setting, etc.
I guess you might need to do a bit more tracing of what goes where (atleast roughly) to make a better guess.

3. The ROR things are kind of a RF / mixed signal "IC" type of thing.
Ericsson uses these a lot to get complex building blocks as a single reusable module.
The smaller ones tend to be VCOs, however these are probably more complex.
You can go ahead and desolder the lid with a hot air soldering station.
If you are careful you won't even damage the circuit below.


EDIT:
I think on your board the VCOs are the four panasonic marked metal lid devices.


Greetings,
Michael

15
Hi all,

I know this is an old thread and not the most popular topic on the forum...
However I think it makes sense to document all my findings on one page so I think it makes sense to keep it up to date.

After the rather dissapointing results from the Aliexpress LDMOS transistors, I decided to buy some proper ones from digikey.
I got some BLP2425M10S250P LDMOS, usally used in industrial heating and CW generator circuits.
It is matched for operation between 2400 and 2500MHz with a max. CW power of 250W (!).

This was around half a year ago but a few weeks ago I decided to finally layout a board for them.
I basically copied the design from the datasheet with minor adjustments on the dimensions to get a better match on standard 0.8mm FR4.

This is the board I came up with:



I milled a basic aluminium enclosure and brass solder plate / heat spreader:



I decided to add some "relief cuts" on the brass heat spreader to make sure that there is no overflow of solder onto the PCB, since I had this problem before.
This seems to have solved it with it soldering perfectly without any overflow.
The aluminium part is just what I came up with on the fly, I didn't plan anything and just started to mill away at the closest junk of aluminium I had.

For soldering, I assembled the whole thing and put the enclosure on my heatplate.
The solderpaste I use reflows at 265°C and the heatplate has no problem to heat up the whole enclosure.
It helps to put some kind of weight onto the LDMOS while soldering so that it doesn't "swin away".
It is also important to use aluminium screws to hold everything together, since you might end up soldering the screws in place otherwise.



After putting in the rest of the components and some feed through caps from some sovjet scrap, it looked like this:



At first I only got a lot of smoke ... I measured twice and still managed to solder in the FET the wrong way around ... that's a good way of losing 55$ in under a second I guess ...  :(
So after replacing the FET I gave it a proper test with my previous MHT1008 eval board amp as a driver.



I can only drive it linearly with around 5W in this setup so I will be far from saturating the final transistor.
It turned out as expected, giving a peak output of around 60W before setteling down on around 50W after the FET heated up a bit (I only put it loosly on a small heatsink, without any heatsink compound)



The gain is somewhere around 12 to 14dB which more or less matches the datasheet (the datasheet calls for a typical value of 15dB and a minimal value of 13dB).
So I guess for a FR4 PCB and without any RF simulation this is quite a usable result.
I guess by integrating all the driving stages and the final onto a single PCB, I might be able to get around 70W out if I'm lucky, which is basically the legal limit for the 13cm HAM band anyway (atleast in Germany).

The amplifier is very stable and linear, without any tendency to fall into oscillation.



That's it for now.
Greetings,
Michael



16
Thanks David,

very interesting insight.
I knew VXWorks as a real time OS, I have seen it used on some data logging / automotive measurement boxes before.

I tried the "lkup" command, there are only 8451 routines  ;)

Code: [Select]
C0->lkup
Number of Symbols   : 8451     
Symbol Mutex Id     : 0x54d49b4   
Symbol Hash Id      : 0x54de554   
Symbol memPartId    : 0x5416628   
Name Clash Policy   : Allowed   
value = 0 = 0x0

The serial output is divided in blocks of 22 lines each, to prevent you from spamming your terminal for forever.
This is one of the many 22 line blocks:

Code: [Select]
_func_rtpSigtimedwait     0x05429098 bss     
_func_kernelRoundRobinHook 0x053f1bf4 bss     
_func_IntLvlDisableRtn    0x052c47c0 data     
VOS_Bind                  0x051e2af8 text     
Shell_Char                0x05000374 text     
NrmLinkAlm                0x05203000 text     
FPGA_8bitReg_ReadU16      0x051e1408 text     
FLASH_WriteMemByIndex     0x05072f98 text     
FLASH_WriteDataToBtrm     0x0503bc9c text     
FLASH_BlockErase          0x0505b440 text     
DBGSHELL_FM_RcvHandleStub 0x050a6a68 text     
CPRI_GetLocalTopoModeInCbb 0x05099500 text     
CLKGENERATOR_CheckChipIndexValidity 0x05041a98 text     
BSP_InstallResetFunc      0x050235d0 text     
tExcTaskExcStk            0x053e8638 bss     
system                    0x050db520 text     
sysctl_node               0x052c63e0 data     
sysExcMsg                 0x052b70ec data     
strcpy                    0x050dba34 text     
sigEvtRtn                 0x053ea630 bss     
shellInternalStrToInt     0x0516ee08 text     

Type <CR> to continue, Q<CR> to stop: semEvStop 

Do you know what the hex value means?
Is it like an routine ID or an actual starting address on the memory stack?





Thanks and greetings,
Michael

17
I also have some news to share.
I found a serial terminal on the mainboard from the unit I took apart.
It isn't protected and you are the admin by default.

Code: [Select]
Board name ..........................HisiCortexA9

Now The <Second> Bootrom is Running............OK

BootRom Version ...........................SECOND
HDF DDRC Init..................................OK
HDF ECC Init...................................OK
HDF BootBus Init...............................OK
HDF HardWare Init..............................OK
This is only a string for loop test............OK

BSP Normal Mode RamExam begin!

RamExam: execute simple exam:
BSP HDF Driver Init............................OK
BSP HDF Version is Main Ver address at 0x80080000
BSP HDF Version is ignore algorithm at first time

RomInit Has Initiated All Parts................OK

Ram Cleaned And Uncompressed...................OK

Move HDF To Ram................................OK
Root Task Spawned..............................OK
Init System MMU................................OK
Init Boot Device...............................OK
Device Tffs: is mounted OK!!


                                                                                                                       
dosChkLib : CLOCK_REALTIME is being reset to WED OCT 26 08:22:36 2022
Value obtained from file system volume descriptor pointer: 0x5461820
The old setting was THU JAN 01 00:00:00 1970
Accepted system dates are greater than THU DEC 27 00:00:00 1990

Tffs:/  - Volume is OK
Target Name: vxTarget

Adding 8819 symbols for standalone.






                          VxWorks System Boot


Copyright 1984-2008  Wind River Systems, Inc.





CPU: HISILICON - CortexA9 (ARM)
Version: VxWorks 6.8
BSP version: 2.0/0
Creation date: Feb  9 2012, 17:18:02



 

 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
      ]]]]]]]]]]]  ]]]]     ]]]]]]]]]]       ]]              ]]]]         (R)
 ]     ]]]]]]]]]  ]]]]]]     ]]]]]]]]       ]]               ]]]]           
 ]]     ]]]]]]]  ]]]]]]]]     ]]]]]] ]     ]]                ]]]]           
 ]]]     ]]]]] ]    ]]]  ]     ]]]] ]]]   ]]]]]]]]]  ]]]] ]] ]]]]  ]]   ]]]]]
 ]]]]     ]]]  ]]    ]  ]]]     ]] ]]]]] ]]]]]]   ]] ]]]]]]] ]]]] ]]   ]]]] 
 ]]]]]     ]  ]]]]     ]]]]]      ]]]]]]]] ]]]]   ]] ]]]]    ]]]]]]]    ]]]]
 ]]]]]]      ]]]]]     ]]]]]]    ]  ]]]]]  ]]]]   ]] ]]]]    ]]]]]]]]    ]]]]
 ]]]]]]]    ]]]]]  ]    ]]]]]]  ]    ]]]   ]]]]   ]] ]]]]    ]]]] ]]]]    ]]]]
 ]]]]]]]]  ]]]]]  ]]]    ]]]]]]]      ]     ]]]]]]]  ]]]]    ]]]]  ]]]] ]]]]]
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]       Development System
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]]
 ]]]]]]]]]]]]]]]]]]]]]]]]]]]       VxWorks 6.8
 ]]]]]]]]]]]]]]]]]]]]]]]]]]       KERNEL: WIND version 2.13
 ]]]]]]]]]]]]]]]]]]]]]]]]]       Copyright Wind River Systems, Inc., 1984-2009

 CPU: HISILICON - CortexA9 (ARM).  Processor #0.
 Memory Size: 0xb000000.  BSP version 2.0/0.
 Created: Feb  9 2012, 17:18:02
 ED&R Policy Mode: Deployed

C0->tool: inflate, unzipped 10858305 bytes, used 0 seconds

[BoardType] XRRU 2T2R

Start over 3, BootRomEntry Starting.......

One interesting detail is, that it will only fully boot beyond this point, if a SFP module is inserted.
After it booted, you need to unplug it again, since it will be stuck in a "trying to get a CPRI connection" loop otherwise.
The classic help command gives you a nice overview of what you can do in this shell.

Code: [Select]
help                           Print this list
dbgHelp                        Print debugger help info
edrHelp                        Print ED&R help info
ioHelp                         Print I/O utilities help info
nfsHelp                        Print nfs help info
netHelp                        Print network help info
rtpHelp                        Print process help info
spyHelp                        Print task histogrammer help info
timexHelp                      Print execution timer help info
h         [n]                  Print (or set) shell history
i         [task]               Summary of tasks' TCBs
ti        task                 Complete info on TCB for task
sp        adr,args...          Spawn a task, pri=100, opt=0x19, stk=20000
taskSpawn name,pri,opt,stk,adr,args... Spawn a task
tip       "dev=device1#tag=tagStr1", "dev=device2#tag=tagStr2", ...
                               Connect to one or multiple serial lines
td        task                 Delete a task
ts        task                 Suspend a task
tr        task                 Resume a task

Type <CR> to continue, Q<CR> or q<CR> to stop: edrHelp


tw        task                 Print pending task detailed info
w         [task]               Print pending task info
d         [adr[,nunits[,width]]] Display memory
m         adr[,width]          Modify memory
mRegs     [reg[,task]]         Modify a task's registers interactively
pc        [task]               Return task's program counter
iam       "user"[,"passwd"]    Set user name and passwd
whoami                         Print user name
devs                           List devices
ld        [syms[,noAbort][,"name"]] Load stdin, or file, into memory
                               (syms = add symbols to table:
                               -1 = none, 0 = globals, 1 = all)
lkup      ["substr"]           List symbols in system symbol table
lkAddr    address              List symbol table entries near address
checkStack  [task]             List task stack sizes and usage
printErrno  value              Print the name of a status value
period    secs,adr,args...     Spawn task to call function periodically
repeat    n,adr,args...        Spawn task to call function n times (0=forever)
version                        Print VxWorks version info, and boot line
shConfig  ["config"]           Display or set shell configuration variables

Type <CR> to continue, Q<CR> or q<CR> to stop:
strFree   [address]            Free strings allocated within the shell (-1=all)

NOTE:  Arguments specifying 'task' can be either task ID or name.

This got me pretty hyped to see what else I can do and I might or might not have bought a complete Baseband unit for it.  ;)



Greetings,
Michael

18
I have found out by now, that companies very seldom smashes up stuff before throwing it out, it is usually the crane operators at the scrap yards that enjoy picking up stuff and let it fall to be smashed in pieces.

Good point, I once saw the scrapyard team "taking apart" a Kuka arm .... they literally smashed it with a hammer in order to "get out all the plastic, since the aluminium is worth more that way"
... well I guess that's one way of doing it


Those cylindrical resonators are kind of special, never saw those types before. Its always been mushroom or hollow tubes.

I haven't seen these all that often either.
Also I stand to be corrected, they are actually conductive from silvered end to silvered end with pretty accurate 500kOhms.


Strong glue or bad solder.... that is the question ;)

Lets hope for the first thing.  ;)

19
Hi all,

first of all, Mads did a great job, showing the 1800MHz model of this Remote radio unit, so go check it out:
https://highvoltageforum.net/index.php?topic=517.0


Now for my story, a few days ago, I had a day off so I went to the scrapyard and checked what they had.
As I was about to leave, I came acrosss a complete (!) Huawei basestation installation.
The 19 inch rack with all the server and baseband stuff was pretty much smashed to dust. The 48V supplies were either missing or so smashed up, that I didn't want to spend any amount of money on them.
The only thing left were some fiber breakout panels, some pretty messed up ethernet switches and a few remains of the baseband stuff, with the main BBU missing. The only thing interesting to me, was this plugin card, so I got it for 4€.





Unfortunately I can't find any information on what exactly this card does but it atleast has some nice SMA connectors to salvage.

Other than that I got two RRU3928 remote radio units for 30€ each.
Both are the 900MHz version with two channels, being full duplex each.
One of the units is pretty smashed to pieces, the other one looks brand new apart from a few scratches on the handle.
So I decided to take apart the damaged one and keep the good one for now.
Both units were made in 2013 so they were 9 years in service before being scrapped.









Since Mads already did a very nice teardown, I try to focus on some of the differences between the 1800MHz and the 900MHz version.
The units both came with both SFD(+) modules populated.



The duplexer unit is similar to the one on the 1800MHz version, with one channel on each side of the casting.
Both sides are fully symmetrical.
Other than the 1800MHz version, the 900MHz one also has some ceramic resonator elements.
These are pretty interesting, they are non magnetic so I guess they are made from some kind of ceramics and not of ferrite.
However both sides are silver plated which I find interesting, since the elements themself are not conductive.
(Maybe for "forcing" them to have a very precise length if the elements wouldn't sit flush with the casing?  ??? )



The ceramic elements are only clamped in by the lid and a small "springwasher".



The power amplifier is of course also different to the 1800MHz version.
The LDMOS transistors use black plastic packages, which seems to be more common for the sub 1GHz FETs.
(That is atleast what I found when looking at the examples I have)
Intersting is the use of two different FETs for each amplifier.
This makes it pretty obvious that they use a Doherty configuration with the higher power FET handling the main part and the lower power FET handling the peaking amp.





The mainboard is basically identical to the one Mads showed.
I guess some filtering etc. is different but the architecture and main components are identical.

Since I have both a really nice looking complete unit and the bare boards from this unit, I might try to see how far I can get with reverse engineering it.
If someone has some CPRI knowledge to share, feel free to cantact me, I'm very interested.  :D





Greetings,
Michael

PS: The glue used on the heatsinks of the plugin card deserves some kind of price.
It was strong enough to rip of the BGAs from the board and then to rip the BGA apart....



20
Light, Lasers and Optics / Re: RF mosfets and laser generation
« on: October 03, 2022, 10:26:07 AM »
Hi dru,

you wouldn't use them to directly generate laser light. You would build an RF source with high CW power output (normally in the 27MHz ISM band).
This generator is then used to ionize some gas to generate a laser beam.
I think it is called something along the lines of "RF doped laser" or "RF doped plasma".

I'm not really an expert in any way in this field, I only reused some of the RF equipment from it.



Greetings,
Michael

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March 17, 2024, 07:42:55 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:15:14 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 05:05:04 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
davekni
March 17, 2024, 04:50:51 AM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Twospoons
March 17, 2024, 04:45:17 AM
post 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:17:51 AM
post Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Terry
March 17, 2024, 01:29:32 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 17, 2024, 12:33:06 AM

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