[hpsdr] Questions

[David McQuate]

Hi Jim,

   I can answer some of your questions--
3.  I & Q values travel both ways--for receive & transmit.  You can use 
either USB interface (Magister or Ozy) or ethernet interface (Metis)
This is standard, used by any of the PC software.

4.  There's been a fair amount of development of system capabilities, 
with the need to make changes to the FPGA code.  You will need to update 
Metis, Mercury, Penelope, Penny Lane boards so they will work with 
current PC software.  Metis is capable of reprogramming itself, Mercury 
or either Penny.  Ozy or Magister can do the same over USB.  Ozy & 
Magister have their FPGA loaded every time they are powered up (no 
on-board flash memory), so you just need to have the appropriate files 
on your computer.

5.   Yes, you'll need PowerSDR designed specifically for HPSDR.  Most 
(if not all) PC software and FPGA code can be obtained directly from
http://openhpsdr.org/download.php
That page also shows the URLs for 3 SVN sites that contain much more.

6.  The standard PowerSDR and KISS Konsole PC programs provide for a 
single receiver using a single Mercury board.  Multiple receivers is a 
newer capability, being developed recently.  There is a new PowerSDR 
version that provides 2 simultaneous receivers (using a single Mercury 
board) each of which can be set to any frequency in the 0.5 to 55 MHz 
range.  A different software package, ghpsdr3 can provide up to 4 
simultaneous independent receivers.  This is better developed on Linux, 
but there's ongoing work to bring that capability to Windows.  Another 
version of PowerSDR allows use of multiple Mercury boards (with separate 
antennas) to provide beam steering (peaking or nulling) on receive.

7.  Metis does not affect receiver or transmitter frequency accuracy or 
stability.  It is only an Ethernet interface between the hardware and 
the PC.  The TCXO on Excalibur is (manually) adjustable to be closer to 
exactly 10.0 MHz than the crystal oscillators on Mercury or Penny boards 
(whose 10 MHz oscillators are not adjustable).  It's more stable, as 
well.  Excalibur can also be used a a way of connecting an external 10 
MHz reference into the system--in which case its own TCXO is not used.

11.  The faster your PC, the lower fraction of its processing power will 
be required for processing the receive & transmit audio streams.  If the 
PC is too slow, there will be dropouts and other "glitches" in the 
audio.  You can change the sampling rate of the receive data streams-- 
48k, 96k, or 192k samples per second when using PowerSDR or KISS 
Konsole.  The lower data rates give you better frequency resolution on 
the spectrum display and lower CPU load.  The higher data rate lets you 
view a wider spectrum (192kHz wide).  You'll want to use a higher 
performance PC if you want to use multiple receivers simultaneously.  
Others will have to comment on specific processors.  I'm using an Intel 
3 GHz Core 2 Duo, and can easily run 4 simultaneous receivers.

73,
Dave
wa8ywq

 1329031937.0