LimeSDR USB Issues

[EA3UM]

Hi Dave
This last week I have been away and I have not been able to continue with the comments of the forum.
With this last update all the problems with the LIME SDR USB seem solved.
A great job. Congratulations.
just one thing:
In https://wiki.batc.org.uk/Using_LimeSDR_with_Portsdown it says that the delayed PTT goes through GPIO 7 (pin 10 header) of the LIME SDR USB and I find it in GPIO 5 (pin 8).
I hope I'm not confused about the position of the header pins, according to Myriad's specifications.
I have not detected any more problems than you have already seen.
Thanks for your attention.
73 - Magi
EA3UM

[G8GKQ]

Hi Magi

Really pleased that it is now working for you.

As for the PTT signal, I do set bit 7; what the LimeSDR USB driver then does with it is a mystery:

Code: Select all

if (gpio_band < 128)
{
  gpio_band = gpio_band + 128;
}
// Set PTT on
LMS_GPIOWrite(device, &gpio_band, 1)!=0)

Anyway, I've added your report to the Wiki. Thanks

73, Dave

[EA3UM]

Hi Dave
More details of the operation with LIME SDR USB.
In Wiki you define: "On the Lime USB the output is from" TX1 Low "below 2 GHz and from" TX1 High "above 2 GHz. The Lime Mini only has a single output."
From the update of Gateware 18 to version 20, I observed that the RF in all the bands, even the 2400 MHz come out through TX1-1 (Before TX1 low).
With Gateware 18 the 2400 MHz output was by TX1 High ... (TX1-2).
These denominations correspond to the latest version of LIME SDR USB.
Really weird is the PTT output delayed by GPIO 5 instead of 7.
I can only say that even before the update of the Gateware, this output was always found in GPIO 5.
Maybe it could be clarifying to try to activate another bit (gpio_band + 64 or gpio_band + 32) ... and see how it reacts.
73 - Magi
EA3UM

[EA3UM]

Hi All
As it seems that we are few who use the LIME SDR USB, I think it could be useful to open a topic dedicated to this board.
It is not my intention to present more problems, but in principle, solved the main initial problems, and in the phase of composing the P.A. To raise the level of RF output, I see new effects that I had not observed in previous versions of the software.
An effect that did not happen in the previous version, is that in "carrier" mode when activating TX, the delayed PTT acts, but when it stops transmitting, it is no longer deactivated ... it remains fixed until it is reset.
Another problem is that with "Lime gain" to 100, and in carrier mode, the RF outputs are:
at 2400 MHs = -13 dBm
at 1250 MHz = 0 dBm.
at 437 MHz = +4.23 dBm.
at 146 MHz = +3.5 dBm
They are low levels according to the manufacturer's specifications.
Then, to obtain a certain RF output power, it forces me to configure an important amplification chain, since at 2400 MHz I need more than 20 dBm. additional
This had not been observed in the latest software versions, but I also have to say that in the face of other problems, it did not require my attention.
I do not know if this could be related to the fact that the RF output is by TX1-1 for all the bands.
I would like to thank Lime USB users for their comments on this.
Thank you all.
73 Magi
EA3UM

[radiogareth]

Following, I too have a Lime USB. At the moment I'm still experimenting on the lower bands. Lime gives easy access to 2.4 on Portsdown for Q100 for me but also have Pluto and Express DVB, SDRAngel etc.
Gareth

[G8GKQ]

I'm opening this topic to discuss LimeSDR USB (not LimeSDR Mini) issues.

Please be aware that I am working in the dark here, as I do not have a LimeSDR USB to test with!

Dave, G8GKQ

[G8GKQ]

Magi

It appears that we have an output switching issue with the LimeSDR USB. That would account for your low output levels.

Have you updated your LimeUSB Firmware/gateware to the correct version for the Portsdown? Please check the Firmware version before any update and m
ake a note of it to post here (from the Console Menu, system setup, Lime Status). Like this:

Code: Select all

LimeSDR Firmware Status
=========================

Make device
  Device name: LimeSDR-Mini
  Expansion name: UNSUPPORTED
  Firmware version: 6
  Hardware version: 2
  Protocol version: 1
  Gateware version: 1
  Gateware revision: 29
  Gateware target: LimeSDR-Mini
  Serial number: 0x1d42596a909fe9
  Free connection... OK

Press any key to return to the main menu

To update you can use the Console Menu, system setup, Lime Update. Then please report back with the Firmware and gateware versions again.

These functions should work the same for LimeSDR USB and LimeSDR Mini.

Dave

[EA3UM]

Hi Dave
Thanks for opening the topic
Yes, I tried to update, but it tells me that it is not required.
Something has changed in this latest version, because in carrier mode it only activates and stays fixed.
In the previous version it worked fine. Of that I'm sure.
As for RF levels, I'm not so sure anymore, because I had other problems and I did not measure.
Keep investigating

noupdate.jpg (37.26 KiB) Viewed 3381 times

73 Magi
EA3UM