DATV-Express SSB / FM Radio Transmitter
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This forum is run by the BATC (British Amateur Television Club), it is service made freely available to all interested parties, please do not abuse this privilege.
Thank you
Re: DATV-Express SSB / FM Radio Transmitter
I suspect there is a work around I will have to check first.
The work around would be to calibrate the Express board using the DATV App
then copy the calibration from the configuration file into the SSB configuration file.
The other issue may well be the frequency stability of the Express board at 2.4 GHz.
The TX frequency is controlled by a 20 MHz SMD oscillator on the board.
On one of my units I have replaced the oscillator with an SMA so I can use
an external GPSDO.
http://g4guo.blogspot.com/2016/06/coupl ... -datv.html
- Charles
The work around would be to calibrate the Express board using the DATV App
then copy the calibration from the configuration file into the SSB configuration file.
The other issue may well be the frequency stability of the Express board at 2.4 GHz.
The TX frequency is controlled by a 20 MHz SMD oscillator on the board.
On one of my units I have replaced the oscillator with an SMA so I can use
an external GPSDO.
http://g4guo.blogspot.com/2016/06/coupl ... -datv.html
- Charles
Re: DATV-Express SSB / FM Radio Transmitter
Yes it does look like that work around would work, here below is the contents of the configuration file for ExpressSDR
# Automatically updated, one space between parameters
set af 21
set rf 36
set freq 2400100000
set mode usb
set mic Microphone (HD Pro Webcam C920)
set fcor 1.000002400000
set ioff 0
set qoff 0
Here are the lines from Express DATV
-21
[Q DC OFFSET] -39
Once the Express board is up to temperature the values shouldn't change much.
For some reason the forum is mangling the Express OFFSET part of my post (bad forum)
- Charles
# Automatically updated, one space between parameters
set af 21
set rf 36
set freq 2400100000
set mode usb
set mic Microphone (HD Pro Webcam C920)
set fcor 1.000002400000
set ioff 0
set qoff 0
Here are the lines from Express DATV
-21
[Q DC OFFSET] -39
Once the Express board is up to temperature the values shouldn't change much.
For some reason the forum is mangling the Express OFFSET part of my post (bad forum)
- Charles
Re: DATV-Express SSB / FM Radio Transmitter
thank you a lot Charles
I will try this evening.
I will try this evening.
Re: DATV-Express SSB / FM Radio Transmitter
Perfect it works correctly with the values you have done.
Thank you a lot Charles !
Thank you a lot Charles !
Re: DATV-Express SSB / FM Radio Transmitter
That is interesting I was expecting every board to need unique values
- Charles
- Charles
Re: DATV-Express SSB / FM Radio Transmitter
I experimented with it last night and it seems the calibration is frequency dependent
so for best carrier suppression it needs to be calibrated near the operating frequency.
Eventually I may add code so it can store multiple calibration points and when a frequency
is selected it chooses the closest one.
- Charles
so for best carrier suppression it needs to be calibrated near the operating frequency.
Eventually I may add code so it can store multiple calibration points and when a frequency
is selected it chooses the closest one.
- Charles
Re: DATV-Express SSB / FM Radio Transmitter
It will be a nice improvement indeed if you could add this feature.
Best 73's
Best 73's