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December 26th, 2016

Implementing API version 2.09, support for RSP2, better AGC and other improvements.

The LNA Gain (aka RF Gain) values depend on a few factors, here's an excerpt from the 2.09 API documentation as applied to this software when using the RSP2:

  • 0 to 4 if High-impedance antenna selected
  • 0 to 5 if tuning (radio) frequency is >= 420MHz
  • 0 to 8 if tuning (radio) frequency is < 420MHz

This software attempts to only use values from this range, otherwise errors are returned from the APi.

 

Driver

The latest Mirics driver (current release: 1.97 20th September 2016) is required [link].

 
September 18th, 2016

Implementing API version 1.97, has New AGC + DC offset schemes.

August 6th, 2016

Implementing API version 1.95. This is a big change and a major improvement.

The available bandwidths (sample rates) are summarised below:

Bandwidth Filter IF Type Notes 
 500 kHz  300 kHz 450 kHz  ~50 ms extra latency.
 1 MHz  600 kHz 450 kHz ~50 ms extra latency.
 2.048 MHz  1.536 MHz 450 kHz Lowest latency, best quality.
Recommended for HF.
 5 MHz 5 MHz Zero  
 6 MHz 6 MHz  Zero  
 7 MHz 7 MHz Zero  
 8 MHz 8 MHz Zero  
 10 MHz 8 MHz Zero  

 

The bandwidths with a 450 kHz IF type have the best spur (DC offset) reduction.

Stuttering Audio!

If the audio stutters and you are using USB 2 then you must start the radio with a lower bandwidth. The USB 2 clock speed is 480 megabits per second, this is shared between all devices connected to the same controller. At 10 MHz the USB bandwidth will be close to the USB 2 maximum once overheads are taken into account.

Options

The menu options are:

  • Low Noise Amplifier (LNA) On/Off
  • Gain - AGC or manual
    • AGC - select a setpoint in dBFS (dB Full Scale) the default is -30, limits are -10 and -70
    • Manual - select gain reduction to reduce gain overload
  • Visual Gain - compensate for variance in the received signal level
  • Radio Configuration, contains help text and diagnostic settings

Driver

Mirics driver 1.95 is required [link].

January 14th, 2016

Implementing API version 1.8.1 .

Mirics driver 1.8.1 is required [link].

October 10th, 2015
  • Correct device initialisation when changing band,
  • Added periodic DC compensation to prevent the ADC overloading,
  • Added selectable 1st local oscillator frequency,
  • Added full band coverage (removed gap in frequency range by switching LO frequency).
July 7th, 2015
  • The user interface has been tidied up, the SDRPlay option menus are shown below,
  • Updated per-band visual gain values,
  • Updated the optimum list of bandwidths (spans) the user has available when starting the radio,
  • Added visual gains.

The LNA Gain Threshold values are not valid for all frequencies, if an invalid entry is selected it is rounded up to the minimum value allowed for the current frequency.

         

June 17th, 2015
  • Removed Radio Configuration button, was shown by mistake,
  • Implemented LNA Threshold, this is the threshold at which the LNA will be switched in,
  • Connection with radio now only reset when changing band,
  • Added visual gain compensation as the default was way too high.

To do:

  • Add automatic AGC as per the Mirics technical note,
  • Determine and then update per-band visual gain values,
  • Decide on the optimum list of bandwidths (spans) the user has available when starting the radio.

A screenshot of version 3 using the SDRPlay RSP receiver

 

Use the Logfile window to see the changes made to the display as you select Options such as LNA Gain Threshold.

Forums

The SDRplay Community Forum is located at http://www.sdrplay.com/community/ .

Feedback

Astounding performance with SDRPlay on V3 Preview 4

That's with the receive bandwidth set to 10 MHz, despite the cautionary note on Simon's website about attempting 10 MHz bandwidth on USB 2. I'm getting perfect audio, no dropouts. And look at the signal strength of the station on Receiver #17 compared to the noise floor - that's a 70 dB dynamic range with a high gain vertical whip and the LNA off. Clean spectrum all the way across (few tiny spikes are local QRM), no IM anywhere - and that's in the Dallas / Ft. Worth metroplex where there are 2 dozen high-power broadcast FM stations.

For anyone considering an SDRPlay, I also noticed this morning that it's selling for $129 at the official website and HRO until the end of the month. NOTE: In the interest of disclosure, I have no affiliation with SDRPlay or HRO, I'm just a very happy SDRPlay user!

Disclaimer: I'm running on a slightly overclocked (4.3 GHz) i7-6700K processor so your results may vary.

Thank you very much, Simon!

Mark KF5VQY

To-Do
  • Ensure the gain reduction doesn’t reset to zero, (Bug)
  • Add Low IF option,
  • PPM correction (like on the dongles – people request this even though when set-up properly it isn’t really a big issue),
  • Maybe add a warning somewhere that if people don’t have plenty of gain reduction the receiver will appear deaf! (typically 60dB minimum on HF).

 
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