47394Re: Advice needed with Ensemble RXTX
- Sep 1, 2010Hi David,
I have not tried having multiple versions of the database, I suspect it might be possible, but it would be easy to get things mixed up continuously swapping over. I must admit I have mine set up for my primary SDR transceiver and use that for all. If you calibrate the Si570 properly using the firmware features you can swap between multiple devices.
The is nothing 'funny' about there being minor frequency differences between different Si570 devices. If you purchased two crystals you would not expect them to be identical. If you take a look at the data sheet for the Si570, you will see the frequency source is a variable oscillator in the mid GHz region/ Producing that on such a small piece of silicon will invariably produce a spread of tolerances. That's exactly why the calibration feature is provided in the firmware. Unless you follow the correct procedure and only use the firmware calibration, you will end up chasing your tail if you set anything in the SDR program itself. The procedure is detailed in the 'Firmware User Guide' and has been discussed on this forum numerous times.
PowerSDR uses a 'pseudo' IF in order to offset the tuning point away from the centre frequency noise. Different frequencies can be set up, in Christos SV1EIA's versions the default is 9kHz, so that will probably be the offset you are seeing.
Are you actually measuring the sensitivity using a calibrated input signal source or just looking at the noise floor relative to the scaling? The different SoftRock designs do have different overall gains, so it would be necessary to calibrate the amplitude within PSDR for both to make any comparison.
Sensitivity for most of the SoftRock SDR designs are very similar.
73, Bob G8VOI
--- In firstname.lastname@example.org, David Garnier <dgarnier@...> wrote:
> I have spent the last couple nights troubleshooting and
> now I'm looking for some advice.
> SDR S/W is SV1EIA's PowerSDR Rev 22.214.171.124
> 1) How do I create multiple radio profiles in PowerSDR? Is it as
> simple as backing up the PowerSDR database to a specific name
> and creating a new database? For example, one profile for
> SoftRock 40, 6.1 RxTX, or Ensemble this! ;-)
> 2) When I initially tested the Ensembles USB section (with DG8SAQ's
> USB synthesizer utility) the Si570 was couple KHz off frequency.
> How weird is that for a new chip?! When I attempted to zero this
> "initial offset" out, it appears *something* is repeatable resetting
> or erasing my newly stored Si570 oscillator cal factor at further
> power-ups. I'm to wonder is something is whacked.
> 3) Addtionally, PowerSDR appears to be adding a couple KHz offset
> to my Si570 LO.
> Meanwhile, as a baseline, my old SoftRock 40 + QRP2000 Si570 USB board
> works FB under this same PowerSDR package.
> 4) Sensitivity of my Ensemble appears to be less than my old SoftRock 40.
> Maybe it's as simple as running PowerSDR calibration routine, but I
> cannot because the LO isn't falling within a predetermined window.
> Thanks for any input.
> Dave Garnier - wb9own
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