SPDPlay Device Controller for Dummies

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Alastair_BKA
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Joined: Wed Sep 09, 2015 3:22 pm

SPDPlay Device Controller for Dummies

Postby Alastair_BKA » Wed Sep 16, 2015 8:29 pm

Is there a SPDPlay Device Controller for Dummies, like if in shortwave you set it to this, VHF you set it to that and so on. I am monitoring around 138 to 143 NFM P25 Phase 1 Transmissions. So any help would be grateful.
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F1BJB
Posts: 108
Joined: Wed Jul 15, 2015 4:24 pm
Location: Beauvais France

Re: SPDPlay Device Controller for Dummies

Postby F1BJB » Fri Sep 18, 2015 8:06 pm

Hi
In fact what you are asking for is hard to do.
Soft ware Defined Radios are mainly limited by what you run the software on .
On the SDR hardware side basic rules of radio applies:
Use an antenna as suited to what you want to receive as possible.
Use as little amplification as possible
Use as little bandwith (sampling rate ) as needed.
I don't know what "NFM P25 Phase 1 Transmissions" are may be satellites meteo ?
138 to 143 MHZ is rather clear from strong signals here but a front end filter is always a good idea.
Satellites transmissions are always rather weak and terrestrial interference can be very strong.
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DaveB
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Re: SPDPlay Device Controller for Dummies

Postby DaveB » Sat Sep 19, 2015 5:04 pm

Not a recommendation as such - but try the following for VHF

LNA gr = 59dB
AGC off
Overall gain reduction 57dB
Leave the ADC set point at -15dB

This will force the low noise amp at the front end - the one inside the mirics chip - on. If LNA gr is less than overall gr - the LNA chip is off. If you don't n=have an antenna pre-amp you will lose s/n ratio with LNA off. The LNA chip between the antenna input and the front end filters is on all the time above 60 MHz.

If you have a high gain pre-amp then run with the LNA gr set to keep the LNA off - it will make no difference to the s/n ratio.

It may be easiest to play about with settings whilst tuned to a weak WFM broadcast station. If satellite work on 138-143 is important you might also consider fitting a filter to block FM signals to avoid breakthrough.

Rgds

David
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Alastair_BKA
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Re: SPDPlay Device Controller for Dummies

Postby Alastair_BKA » Thu Sep 24, 2015 3:35 pm

Thank you for all the good information
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