[digitalradio] ROS on UHF

Sun, 21 Mar 2010 06:43:08 -0700 

Extensive testing of ROS on the air on UHF have now been concluded.
Unfortunately, ROS totally fails for UHF communications, in either 16 baud, or 1 baud variants, and using either the HF or EME channel.
Even with ROS metric readings between -1 dB and -8 dB (i.e. relatively strong signals), ROS only printed on 16 baud or on 1 baud as long as the tones sounded "pure" in the headphones, but as soon as the tones sounded "wobbly" and became broadened on the waterfall, decoding became total garbage.
When SSB phone was understandable (but with significant "flutter"), ROS still would not print, even after a successful Frame Acquisition and Symbol Synchronization and print of the callsigns.
We switched to Olivia 32-1000 and print was perfect, as expected, as signals were strong, even though QSB and "flutter" could be heard.
The problem is that ROS is apparently completely destroyed by what is appears to be "Doppler flutter" (for want of a better term), which is present on UHF most of the time. Under those conditions, the spread spectrum technique used in ROS 16 baud and ROS 1 baud modes simply does not survive the Doppler disturbances, whereas Olivia is a multitone FSK mode and does very well. The ROS 500 Hz FSK variants were not tested, as the hope was that the spread spectrum variant of ROS would outperform Olivia, but instead it did much worse. Olivia 16-500, as a reference, almost equals CW in ability to work near the noise, so we were hoping that ROS would work under the noise, but it did not.
Apparently, spread spectrum is just a poor choice whenever there is Doppler-induced distortion like there usually is on 70cm. When I use two transceivers and computers locally, where there are no Doppler effects, all the ROS variants work perfectly, but in real life conditions, where we are faced with QRM, QSB, multipath, and unstable atmospheric moisture conditions that cause fast frequency shifts (apparently Doppler-induced disturbances), ROS fails completely.
As Olivia has been designed to accommodate all the difficult conditions we have to deal with on both HF and above, Olivia is a much better choice, and at half the bandwidth, at the same typing speed.
This concludes our tests with ROS and there will be further testing or use of ROS by this station.
ROS spread spectrum is legal to use in the US above 222 MHz, so if anyone else can make such tests, please post the results here. 

73 - Skip KH6TY




[email protected] wrote:

There are 7 messages in this issue.

Topics in this digest:
1a. Re: Scanning PSKmail WARC freqs From: Rein Couperus
2. space to ground audio channels via SDR From: Andy obrien
3a. Has anyone tried the WINMOR keyboarding? From: Howard Z 3b. Re: Has anyone tried the WINMOR keyboarding? From: Andy obrien
4a. Net14 + PK-63 From: G0JXN Jim 4b. Re: Net14 + PK-63 From: Andy obrien 4c. Re: Net14 + PK-63 From: Andy obrien 


Messages
________________________________________________________________________
1a. Re: Scanning PSKmail WARC freqs
    Posted by: "Rein Couperus" [email protected] pa0r
    Date: Sat Mar 20, 2010 2:09 am ((PDT))

The PSkmail servers only use CALL de CALL when confirming messages or user 
beaons...
If you have captured PSK250 then it will probably have been US servers, or 
Intermar maritime
servers on 10148.0 (center freq) (DK4XI-30), as on 10147.0 we use PSK500R as default. 
As soon as a connection is established, RSID is only used for the mode change 
protocol,
and a lot of users don't use the software supporting the new protocol yet...

Rein PA0R


Rein et al.

 I scanned 10147 and 18105 today for six hours, alternating every 90
 seconds with a 3 Khz range.  I only picked up  three PSk250 RS IDs on
 30M and NONE on 17M.  Each RS ID on 30M was not decoded well enough to
 produce a callsign.  Since Muktipsk looks for a "de ****** " string,
 perhaps the stations were sending PSKMAIL IDs without a "de" ?  For
 the last hour , I listening for 30 minutes on each frequency, listened
 with my own ears.  I heard no PSK250 on 18105 .  On 30M I heard two RS
 IDs and several PSK250 signals without RS ID.  perhaps not all PSK
 mail servers are using RS ID yet ?

 Andy K3UK










Messages in this topic (3)
________________________________________________________________________
________________________________________________________________________
2. space to ground audio channels via SDR
    Posted by: "Andy obrien" [email protected] obrienaj
    Date: Sat Mar 20, 2010 1:05 pm ((PDT))

While not exactly digital modes...


---------- Forwarded message ----------
From: pauljmarsh <[email protected]>
Date: Sat, Mar 20, 2010 at 3:07 PM
Subject: [SDR-IQ] Re: Impressions on SDR-IP
To: [email protected]





Some impressions of the IP is at http://www.pudxk.blogspot.com/73,Tarmo...


Hi Tarmo,all,

Thats a very interesting write up. I've put my observations on the SDR-IP
online at http://www.uhf-satcom.com/sdr-ip/

During the last shuttle mission we used an SDR-IP to record the 2MHz
downlink from the shuttle during every pass, resulting in 5Gb to 7Gb files
per pass, which were then post-processed in order to recover the space to
ground audio channels. The mission audio we recovered is posted on line at
http://www.uhf-satcom.com/sounds/ - pretty amazing that it was possible for
non-NASA folks to get this stuff.

The SDRIP here is connected to a giga-bit ethernet LAN, so the network use
is consequentially quite small even with 2Mbps sample rate of the SDR. The
PC used with SV is an Athlon 2.7GHz CPU which seems to be able to keep up
with the network traffic with no problems. I must actually try my SDRIP on
HF a bit more, so far its had about 1 hours use on that band.

regards,

Paul M0EYT.

 __._,_.




Messages in this topic (1)
________________________________________________________________________
________________________________________________________________________
3a. Has anyone tried the WINMOR keyboarding?
    Posted by: "Howard Z" [email protected] howard_z
    Date: Sat Mar 20, 2010 6:16 pm ((PDT))

Hi,

Has anyone tried the WINMOR keyboarding mode - no ARQ using FEC?

How does it compare to Olivia?

Howard






Messages in this topic (2)
________________________________________________________________________
3b. Re: Has anyone tried the WINMOR keyboarding?
    Posted by: "Andy obrien" [email protected] obrienaj
    Date: Sat Mar 20, 2010 6:22 pm ((PDT))

I have the latest version and do not see any keboard method in WINMOR.

Andy K3UK

On Sat, Mar 20, 2010 at 9:14 PM, Howard Z <[email protected]> wrote:


Hi,

Has anyone tried the WINMOR keyboarding mode - no ARQ using FEC?

How does it compare to Olivia?

Howard






Messages in this topic (2)
________________________________________________________________________
________________________________________________________________________
4a. Net14 + PK-63
    Posted by: "G0JXN Jim" [email protected] g0jxn
    Date: Sat Mar 20, 2010 9:24 pm ((PDT))

Hi Guys

As an experiment I have set up APRS/PSK-63 along side the Net14 300bd APRS on 
20m. The 300bd APRS is running at 100W and the APRS/PSK-63 at 25W.

Full details of the setup are available at www.net14.org.uk under Net14 + 
PSK-63.

Reports and comments please.

73

Jim, G0JXN/MB7UXN




Messages in this topic (3)
________________________________________________________________________
4b. Re: Net14 + PK-63
    Posted by: "Andy obrien" [email protected] obrienaj
    Date: Sat Mar 20, 2010 11:32 pm ((PDT))

My beacon is

K3UK-14  [FN02HK ].

I also produce


K3UK>APSK63:K3UK FN02hk
K3UK>APSK63:K3UK FN02hk
K3UK-14>APSK63:::{1
K3UK-14>APSK63:::{1
K3UK-14>APSK63:::{1

while playing around..



On Sun, Mar 21, 2010 at 2:15 AM, Andy obrien <[email protected]> wrote:


Thanks Jim.  I have the software and am giving it a try in PSK63 mode ,
software seems to be working but I have a few questions.

Are ALL  the frequencies listed on the web site for PSK63 as well as Packet
?  Also, it has been a while since the days of using UI-View, do I put my
grid in the HF beacon or do you need my longitude /latitude?


Andy K3UK



On Sat, Mar 20, 2010 at 8:28 AM, G0JXN Jim <[email protected]> wrote:


 Hi Guys

As an experiment I have set up APRS/PSK-63 along side the Net14 300bd APRS
on 20m. The 300bd APRS is running at 100W and the APRS/PSK-63 at 25W.

Full details of the setup are available at www.net14.org.uk under Net14 +
PSK-63.

Reports and comments please.

73

Jim, G0JXN/MB7UXN






Messages in this topic (3)
________________________________________________________________________
4c. Re: Net14 + PK-63
    Posted by: "Andy obrien" [email protected] obrienaj
    Date: Sat Mar 20, 2010 11:34 pm ((PDT))

Perhaps this is more like it...


K3UK-14>APSK63:K3UK-14  [FN02HK ].



On Sun, Mar 21, 2010 at 2:32 AM, Andy obrien <[email protected]> wrote:


My beacon is

K3UK-14  [FN02HK ].

I also produce


K3UK>APSK63:K3UK FN02hk
K3UK>APSK63:K3UK FN02hk
K3UK-14>APSK63:::{1
K3UK-14>APSK63:::{1
K3UK-14>APSK63:::{1

while playing around..




On Sun, Mar 21, 2010 at 2:15 AM, Andy obrien <[email protected]> wrote:


Thanks Jim.  I have the software and am giving it a try in PSK63 mode ,
software seems to be working but I have a few questions.

Are ALL  the frequencies listed on the web site for PSK63 as well as
Packet ?  Also, it has been a while since the days of using UI-View, do I
put my grid in the HF beacon or do you need my longitude /latitude?


Andy K3UK



On Sat, Mar 20, 2010 at 8:28 AM, G0JXN Jim <[email protected]>wrote:


 Hi Guys

As an experiment I have set up APRS/PSK-63 along side the Net14 300bd
APRS on 20m. The 300bd APRS is running at 100W and the APRS/PSK-63 at 25W.

Full details of the setup are available at www.net14.org.uk under Net14
+ PSK-63.

Reports and comments please.

73

Jim, G0JXN/MB7UXN






Messages in this topic (3)



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