[Skimmertalk] New info. about running Skimmer using the latest 0.97 Red Pitaya OS

[Bob Wilson, N6TV]

*Summary:*

   - Ignore my previous warnings.  All Red Pitaya's shipping with OS v0.97
   actually do install and run Pavel Demin's *SDR Receiver compatible with
   HPSDR **(0.94) *just fine using the built-in web installer.  But you
   must modify */etc/rc.local* to get it to start automatically at boot
   time.

   - For RTTY Skimming on Windows 7 or later, ignore *"C:\Program Files
   (x86)\Afreet\RttySkimServ\RttySkimServ.ini" (if any).*  Instead, edit
   *"%appdata%\Afreet\Products\RttySkimServ\RttySkimServ.ini"* to match
   center frequencies, segments, *and* *FreqCalibration* used by CW Skimmer
   Server.

   - To run HDSDR while skimming, you have to install *IPP51* in addition
   to

*CWSL_Tee *
   - Use a 5V fan to keep it cool

*Details:*

Thanks to direct email help from SDR developer Pavel Demin, I've learned a
lot about the Red Pitaya operating systems in the last few days, and I need
to update some of the incorrect statements I originally posted about
installing the SDR software required to start skimming (see
http://hamsci.org/n6tv-red-pitaya-combine-cw-rtty-skimmer).  The
previously-documented method using Pavel's pre-built "0.95 ecosystem" SD
card image works fine, but you will be installing an out-of date and quite
limited "BusyBox" Linux operating system that has several limitations,
including:

   1. The root password is not retained between power cycles
   2. The clock is not set automatically at power-up
   3. A RAM disk used, so any changes or logs written to the local file
   system disappear between power cycles
   4. There is no easy way to install useful software tools using the handy
   "apt-get" command (e.g. apt-get install dos2unix)
   5. The command prompt doesn't display the standard hostname (rp-XXYYZZ)
   or the current working directory name

In contrast, the current OS shipped with new Red Pitayas (v0.97) is a
full-function Ubuntu version 16 operating system, and it does not have *any*
of the limitations listed above.  It automatically sets the clock to UTC,
provides a useful command prompt string, and any changes to the root
password or file system are always retained across power cycles.

Ubuntu seems to be the strategic direction for future Red Pitaya software
releases, and some of their apps will require it.  FYI, version "0.96" was
yet another Red Pitaya Linux variant OS called "Debian."  It's also
full-function, but it seems the Red Pitaya developers have decided to go
with Ubuntu instead.

The good news is that it is *much easier* to install the required SDR
receiver software now.  Contrary to what I posted at first, Pavel Demin's *SDR
Receiver compatible with HPSDR (0.94)* works quite well with Skimmer on the
version 0.97 operating system, and you can *easily *install and run it
using the web page that runs on the box.  What I failed to understand when
I first tried that, is that you have to keep your Windows web browser *open*
*after* you click "Install" and "Run," otherwise the receiver stops running
as soon as you close the web page, and Skimmer won't work.

Fortunately, there's an easy way to install the right SDR Receiver *and* have
it start automatically at boot time under 0.97, with no need to open a web
browser to manually start it, and no need to build a new microSD card.  So
here are the steps:

   1. Power up the Red Pitaya using the microSD card image shipped with new
   units.  If you already wiped it out, you can recreate it by following all
   the steps here
   <http://redpitaya.readthedocs.io/en/latest/quickStart/SDcard/SDcard.html>.
   I've tried both "Stable" and "Beta" 0.97 operating systems, and they both
   work.
   2. Determine the IP address assigned to the Red Pitaya.  From Windows,
   the command *ping rp-XXYYZZ* may reveal it, where XXYYZZ represents the
   last six digits of the MAC address printed on the Red Pitaya's Ethernet
   connector.  Your router will also display the assigned IP address, or the
   Windows command *arp -a* may as well.
   3. Open a web browser and go to http://192.168.1.xx (use whatever IP
   address was assigned to your Red Pitaya by your Router)
   4. Click on the green *Application marketplace* icon
   5. Scroll down to the *SDR Receiver compatible with HPSDR* (not the
   other receiver), and click *Install*
   6. It should finish installing in less than 30 seconds, then click *Run*
   7. At this point as long as you don't close the web page that opens
   after you click Run, you can start your Skimmer Server software and it
   should find the Red Pitaya (use the 17.7.6 HermesIntf.dll as described in
   my original post linked above)
   8. Exit Skimmer Server and close your web browser (in that order).  This
   will terminate the receiver.

Once installed and tested, to make the SDR Receiver run automatically
whenever the Red Pitaya is rebooted, just edit or replace the file named
*/etc/rc.local* on the machine (once).  It needs to have two lines added
before the exit 0 command, so the end of the file looks like this

# Start the SDR Receiver compatible with HPSDR at boot time
cat /opt/redpitaya/www/apps/sdr_receiver_hpsdr/sdr_receiver_hpsdr.bit
>/dev/xdevcfg
. /opt/redpitaya/www/apps/sdr_receiver_hpsdr/start.sh

exit 0

The dot ( . ) on the 3rd line above is *required*.

Rather than trying to cut and paste this, I've placed a copy of this edited
file at http://www.kkn.net/~n6tv/rc.local .  Here's the easiest way to copy
it to the Red Pitaya:

   1. Install Putty <http://www.putty.org/> for Windows and open an SSH
   connection (like a TELNET connection) to the Red Pitaya's IP address.

   Userid: root
   Password: root

   2. You should see a login message at the very top that says:

   Welcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-xilinx armv7l)

   or similar

   3. If you haven't done so already, change the root password using the
   command:

   passwd

   4. Enter the following five Unix commands in sequence:

   cd /etc
   mv rc.local rc.local.old
   wget http://www.kkn.net/~n6tv/rc.local
   nano rc.local
        (Verify the file's contents match what I've documented above.
   Press Ctrl-X to exit the nano editor.)
   reboot

At this point, the ssh session will terminate, but when the machine
reboots, and the "heartbeat" LED is blinking, the SDR receiver will be
running, and you'll be able to start skimming using the latest Red Pitaya
OS.

Warning:  do *not* open the Application marketplace from the web browser
while the SDR receiver is running, otherwise the SDR receiver may halt.
>From the Ubuntu command prompt you can manually stop the receiver by
running:

/opt/redpitaya/www/apps/sdr_receiver_hpsdr/stop.sh

Finally, I left out one important step when describing how to use HDSDR to
listen to the Red Pitaya receiver while it is skimming.  In addition to
copying *CWSL_Tee.dll* to the HDSDR installation directory, and
selecting *CWSL_Tee
on RP-XXYYZZ* in Skimmer Server, you must download and install IPP51
<https://github.com/HrochL/CWSL/blob/master/bin/IPP51.zip?raw=true>.

The procedure is well documented here:

http://www.reversebeacon.net/downloads/aggregator/Running-RT
TYSkimServer-and-CW-SkimServer.pdf

The only thing I can't do (yet) on this new OS is monitor the FPGA
temperature while the receiver is running.  I found a shell script called
xadc.sh
<https://raw.githubusercontent.com/RedPitaya/RedPitaya/master/Examples/xadc/xadc.sh>
that works OK when the receiver is stopped, but it locks up the Red Pitaya
immediately if you run it while the SDR Receiver is running, and the only
way to recover from that lockup is to power off and on.

Previous temperature measurements returned by *xadc_get_value_temp* when
running the 0.95 image on BusyBox image revealed:

Red Pitaya with aluminum "heat sink" enclosure, no fan:

~78° C. (scary, 85° C. is max rating)


Red Pitaya with aluminum "heat sink" enclosure and a small fan bolted to
the top center (I had to drill mounting holes and bend the connector pins
on the board to fit the connector):

~68° C.

FreqCalibration=1.00000355

Red Pitaya in plastic enclosure with original heat sink, and a fan mounted
on *top* of the plastic enclosure:

~58° C.

Red Pitaya in plastic enclosure with fan mounted *inside* the enclosure,
with one corner crew touching the heat sink:

~50° C.

FreqCalibration=1


The last solution is best, but it is also the noisiest.  I used two small
4-40 Nylon nuts and bolts to mount the 30 mm x 30 mm x 10 mm 5 VDC fan. The
positive connector pin is the one closest to the center of the board.

73,
Bob, N6TV