[hpsdr] HERMES schedule question

[Phil Harman]

Hi Ray,

A warm welcome to the group, answers to your questions below.

73's Phil... VK6APH


> ***** High Performance Software Defined Radio Discussion List *****

>
> 1) What level are the RX spurs?

I don't have the list in front of me but I think the largest ham band one
was a single spur at -107dBm on 15m. The rest were at the noise floor,
-135dBm.  Our aim is to repeat the spur performance of Mercury which has
no ham band spurs.


> 2) Have you discovered a correlation to any specific on-board source?

Some - hence the changes to the PCB layout presently in train.


> 3) Am I correct about the following?
>     a) The USB MCU is functioning as planned.

Correct.

>     b) Able to program the FPGA through the USB MCU.

Correct.

>     c) FPGA DSP path is working (or nearly complete).

Correct - I am presently using an Alpha PCB as my main station
transceiver, over 100 QSOs with Europe so far. The code to control the
Apollo LPF/ATU and the 0-55MHz band scope needs to be added but both very
simple.

>     d) Signal integrity issues appear to be the final hurdle.
>

We did have a Verilog issue with the Transmit code but this has now been
fixed. The transmitter is now as good as Penelope but with flatter
gain/frequency and better IMD at very low power levels.

The 122.88MHz master clock was being amplified by the PA but PCB tracking
changes will fix this.

Kjell has also designed a superb 13.8v to 5v SMPSU that will be
incorporated in the Gamma PCB. So apart from the Rx spurs we are close.

Hopefully the next spin of the PCB will fix these - we have been here
before (spurs) with the Mercury board, and was able to cure those, so
confidence is high.

We have versions of  PowerSDR and KISS Konsole that support Hermes ready
to roll.

If you have PCB EMI layout experience then you are going to be even more
welcome to the group!





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