Pluto SDR mod gives 56mhz I/Q ?!?!

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Tim Bucknall
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Joined: 01 Oct 2014 14:55
Location: Congleton, often in the Peak District
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Pluto SDR mod gives 56mhz I/Q ?!?!

Post by Tim Bucknall » 14 Mar 2018 10:09

Wondering if I misunderstood what was meant by 20 MHz "bandwidth" before mod and 56mhz after.
seems too good to be true at that price, £100 approx

pity analog TV on band 3 &UHF is gone!

56mhz could grab 48-104mhz , great for studying props

Out of the box coverage is 325mhz -microwave, a mod expands coverage to the stuff we care about
Cons:
Sound like its frontend would struggle in urban locations without external filters
But it would probably be fine for people in skegness called John Faulkner who want to record the whole FM band
Home:Burkhardt Reuter RDR54D1 SDR V.415,
+ CLP 5130 Log P ant

Mobile: Comm Radio CR-1 + Sharman Skyscan ant, Pira P275

daveB
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Joined: 07 Oct 2014 16:49

Re: Pluto SDR mod gives 56mhz I/Q ?!?!

Post by daveB » 14 Mar 2018 13:41

[Moderators - could we have a separate Sub-Group for SDR]
Wondering if I misunderstood what was meant by 20 MHz "bandwidth" before mod and 56mhz after. seems too good to be true at that price, £100 approx
The LimeSDR mini is £100 and appears to offer the same facilities - SDR Console v3 supports it. It will comfortably span the entire FM band as it has a 66 MHz sample rate = 33 MHz b/w. No front end filtering - so that would be needed. [But SDR console only records 2 gB file length so you would get ,30 seconds per file!]
The PlutoSDR can tune from 325 to 3800 MHz. It has an ADC which can sample at up to 61.44 MSPS with a resolution of 12-bits. There is no TCXO used, so the frequency accuracy is only 25 PPM. Although the maximum sample rate is 61.44 MSPS, the front end AD9363 only has a maximum signal bandwidth of 20 MHz, so that limits the available bandwidth. Source: rtl-sdr.com
https://www.rtl-sdr.com/adalm-pluto-sdr ... l-testing/

If you want to study propagation - then Airspy one or Airspy Mini with SDR# has a separate program - Spectrum Spy - that shows the whole spectrum - with choices of 10, 20, 50, 100, 200, 500 MHz band width - and 1 GHz. So 50 MHz would give 65 - 105 MHz, or 100 MHz will give 35 - 135 MHz. The wider the bandwidth chosen - the slower the refresh rate.
But buy one quickly as they are definitely discontinued - Moonraker had 'plenty' of Airspy minis in stock as of 12th March
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

daveB
Posts: 1219
Joined: 07 Oct 2014 16:49

Re: Pluto SDR mod gives 56mhz I/Q ?!?!

Post by daveB » 14 Mar 2018 22:35

Here is an example of Spectrum spy running in 20 MHz bandwidth. Unfortunately what it is showing is some of the after dusk interference affecting the range of 60 - 120+ MHz.
OIRT Band 20 MHz bw 22.32.02.png
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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