Re: [digitalradio] Question on bandwidth on HF

[Andy obrien]

It is a very NARROW mode

On 7/21/10, Russell Blair  wrote:
> THIS IS NOT TO START A BIG THING...I was using one of the new modes today
> WSJT8
> Beta and was informed that the bandwidth exceeded to limits on HF... My
> question
> What is the bandwidth ?
>
> Russell NC5O
>  1- Whoever said nothing is impossible never tried slamming a revolving
> door!
> 2- A government big enough to give you everything you want, is strong enough
> to
> take everything you have.
>
> - Gerald Ford
>
>
> " IN GOD WE TRUST "
>
>
> Russell Blair (NC5O)
> Skype-Russell.Blair
> Hell Field #300
> DRCC #55
> 30m Dig-group #693
> Digital Mode Club #03198
>
>
>
>

-- 
Sent from my mobile device

Re: [digitalradio] Question on bandwidth on HF

[Rudy Benner]

JT8 is proposed as a possible alternative to JT4. Modulation is 8-FSK at 2.857 
baud. FEC uses convolutional codes with K=14, r=1/4, K=15, r=1/6, or K=16, 
r=1/8, depending on message length. Synchronization uses 8×8 Costas arrays at 
the beginning and end of a transmission, followed by two additional symbols to 
distinguish between 30-bit, 48-bit, and 78-bit messages. Total bandwidth is 23 
Hz. At present, only the 78-bit messages have been implemented. 

http://www.physics.princeton.edu/pulsar/K1JT/WSJT8_User.pdf



VE3BDR



From: Russell Blair 
Sent: Wednesday, July 21, 2010 9:46 PM
To: Digital Radio 
Subject: [digitalradio] Question on bandwidth on HF


  
THIS IS NOT TO START A BIG THING...I was using one of the new modes today WSJT8 
Beta and was informed that the bandwidth exceeded to limits on HF... My 
question 
What is the bandwidth ?

Russell NC5O
 1- Whoever said nothing is impossible never tried slamming a revolving door!
2- A government big enough to give you everything you want, is strong enough to 
take everything you have. 

- Gerald Ford 

" IN GOD WE TRUST " 

Russell Blair (NC5O)
Skype-Russell.Blair
Hell Field #300
DRCC #55
30m Dig-group #693
Digital Mode Club #03198 










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02:36:00

Re: Re: [digitalradio] Re: Olivia vs. RTTY vs. PSK & spectrum efficiency

[k3mm]

I think the key to making it really fly would be to hold some short sprint 
contests using PSK63 only.  That way you could get a lot of guys to try it 
without a big commitment of time and effort.  As it gains acceptance thru that 
and word of mouth, it could be added as an optional mode in more mainstream 
contests.

Hold some sprints and talk it up on the email reflectors and it stands a 
chance...

Ty K3MM


Jul 20, 2010 07:10:30 PM, digitalradio@yahoogroups.com wrote:

> 
> 



PSK63 was developed as an intended RTTY contesting mode replacement, 
>not for conversation. PSK31 is too slow for contesting and has a preamble and 
>a 
>postamble that slows turnovers down, so the idea was that 100 wpm PSK63 would, 
>overall, including faster turnovers than PSK31, be as fast as RTTY for contest 
>exchanges, and contesters would benefit from less power needed, panoramic 
>reception, 
>less crowding, and faster synchronization. In the contesting world, a rapid 
>exchange 
>and turnover is more important than a faster typing speed. Peter Martinez 
>designed PSK31 
>for ragchewing and so selected 50 wpm as fast enough for conversation for most 
>typists.
> 
> Even though Don, AA5AU, a big-time winner of RTTY contests, said he was just 
>"blown away" about the possibility of PSK63 for contesting when I showed it to 
>him, I was unable to get it implemented into WriteLog, as the author took a 
>"chicken 
>and egg" approach in which he said he would not add PSK63 to WriteLog until it 
>became popular for contesting! Since WriteLog is so popular with contest 
>winners, 
>and did not support PSK63, the mode never took off, except in Europe.
> 
> What might help would be for someone to convince the contest managers to do 
>something like adding a multiplier for PSK63 contacts, or perhaps some other 
>acceptable 
>incentive, to make it worthwhile to use PSK63 for contests.
> 
> Everybody would win, because so many PSK63 signals can fit into the space 
>of one RTTY signal, and with panoramic displays, you get a list of callsigns 
>to 
>select from all presented to you, and can even highlight zones or callsign 
>areas 
>you need for multipliers, etc..
> 
> 73, Skip KH6TY
> 
> On 7/20/2010 7:03 PM, Ralph Mowery wrote: 
> 

> 
> - Original Message 
> From: g4ilo 
> To: mailto:digitalradio%40yahoogroups.com"; target="_blank" class=" 
>parsedEmail">digitalradio@yahoogroups.com
> Sent: Tue, July 20, 2010 4:29:15 AM
> Subject: [digitalradio] Re: Olivia vs. RTTY vs. PSK & spectrum efficiency
> 
> Just because a mode is better doesn't mean that people will want to use it, 
>
> though, and I guess both RTTY and PSK31 are so established now that you'll 
>never 
> persuade people to give them up.
> 
> Julian, G4ILO
> 
> 
> 
> While rtty can be replaced by other modes, they will not run on the 50 plus 
>old 
> mechanical printers and the demodulators that go with them. Just as some 
>like 
> to run AM on the ham bands. Not that good of a use of bandwidth, but just 
>
> something to play with that many enjoy. I doubt that many 
>hams that run the 
> digital modes can really type very fast and depend on the micros in the 
>
> programs. For the ones doing it in real time, psk31 probably has enough 
>speed.
> 
> 

RE: [digitalradio] Re: ROS back bigger and better !

[Lester Veenstra]

Hi Ted: Concur, which is why I simply created the internal email filter with
the rule, scan any msg in the inbox for the word ros, and place in the Junk
Mail folder for disposal along with the offers for blonds, diplomas from
MIT, and “enhancements”.

   73

 Les 

 

 

 

Lester B Veenstra  MØYCM K1YCM

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From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On
Behalf Of Ted Bear
Sent: Tuesday, July 20, 2010 8:22 PM
To: digitalradio@yahoogroups.com
Subject: [digitalradio] Re: ROS back bigger and better !

 

  

Holy Moly.. When you guys going to drop the ROS subject and get back to
interesting DIGITAL 

AW: [digitalradio] 70cm -2M-6M-10M fan dipole ?

[Siegfried Jackstien]

What about a multiband verticl fort he uppoer bands .. Stacked with some
gain like the x 510 or the x 6000

Omnidirectional . 2 or 3 bands . with some gain . can be used also for local
repeater or emergency work .

Just an idea

For 6 and 10 better use a small beam 

But you can start with a ladderline fed dipole for 6 and 10

Many antannas possible so I would sax . see what you have in your junk box
and garage . and then make something with that parts.

Greetz

Dg9bfc

Sigi

 

 

Re: [digitalradio] 70cm -2M-6M-10M fan dipole ?

[KH6TY]

Andy,

You first have to decide if you will use horizontal or vertical 
polarization - vertical polarization mostly for working the repeaters on 
2M and 70CM, or horizontal polarization for working SSB stations.

Omnidirectionality is easy with vertical polarization but much more 
difficult with horizontal polarization. If you will be working 
repeaters, you do not need much antenna gain, but for SSB, you need much 
more gain.

The other question is the feedline. What transceiver are you using? Does 
it have separate antenna outputs for 2M and 70 CM? For example, on the 
IC-706MKIIG, the 2M and 70 CM antenna outputs are combined, so you can 
use a diplexer to send the RF to the two antennas from a single 
feedline. The 6M output is combined with the HF output, so that requires 
a separate feedline. You probably want horizontal polarization for 6M, 
and an aluminum dipole would be self-supporting. If you use two at 90 
degrees and switch feedlines with a switch, you have omnidirectional 
coverage on 6M.

On 2m and 70 CM horizontal polarization, I use bi-directional skeleton 
slots for each band, which gives me enough gain for DX, mount two at 90 
degrees to each other and just switch feedlines for omnidirectional 
coverage.

If all you are interested in is working repeaters, then a dipole for 6M 
and commercial 5/8 wavelength verticals for FM on 2M and 70CM will work 
with one feedline if diplexers are available to split 6M and 2m/70CM. 
Again, much depends on the antenna outputs of the transceiver, whether 
you should use a single feedline or two feedlines.

73, Skip KH6TY



On 7/20/2010 8:58 PM, obrienaj wrote:
>
>
> I am planning another HF installation soon and may have a 33ft mast
> begging for some extra creative thing to hang off it . I do not do 70cm
> -2M-6M much and think I should , just to be able to get out when there
> are bands openings. Nothing with DX in mind, just something
> omni-directional would do (or ANY direction) I was thinking about a
> fan-type dipole , one feed line going to dipoles for 70cm - 2M - 6M and
> maybe 10M. Most likely not fully horizontal , more of a sloper. Any
> thoughts on something like this? Quite a wide range of frequencies.
>
> Andy K3UK

Re: [digitalradio] Hey ..Good luck! e--5

[Andy obrien]

Member removed.

Andy K3UK


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Re: [digitalradio] ROS HF Path Simulations wide vs. narrow

[KH6TY]

Thanks for the testing Tony. We observe Doppler shifts of as much as 100 
Hz and Doppler spreads around 50 Hz or greater. On SSB phone, a S3 
signal will not be intelligible and you can hear the voice pitch go down 
in a fluttering manner. ROS definitely produces nothing but garbage when 
SSB phone is not understandable, but Contestia will keep on printing 
perfectly.

That is just one more reason that there are better modes than ROS we can 
use, are of much less bandwidth, and equal of better sensitivity.

As someone pointed out, spread spectrum is basically used for encryption 
and has no advantage in disturbed environments.

BTW, it is interesting to note the huge impact of Pawel Jalocha has on 
the use of digital on the ham bands. His SLOPSK development was the 
basis for G3PLX's PSK31, and now, Olivia is the highest performing 
digital mode. It is as if he were the "father" of all we are working 
with today! I wish I knew more about his background.

73, Skip KH6TY

On 7/21/2010 12:15 AM, Tony wrote:
>
>
> On 7/20/2010 3:54 PM, KH6TY wrote:
>
>  >Our on-air tests show that ROS 16 baud, 2200 Hz wide spread spectrum
> was very poor on UHF under Doppler >spreading. Can you confirm this with
> flutter tests like Jaak has done.
>
> Skip,
>
> My path tests show that ROS is less tolerant to Doppler spread than
> Olivia or one of it's variants so I'd have to agree with your on-air
> evaluation. Throughput starts to fail as the Doppler spread is increased
> beyond 20Hz (two channels 2ms delay) and I suspect you could be
> experiencing frequency dispersions beyond that range.
>
> I haven't been able to find any propagation data that shows how much
> Doppler spread is likely take place on VHF/UHF. Wish I knew that answer
> to that.
>
> Tony -K2MO
>
>
>
>> Tony,
>>
>> Our on-air tests show that ROS 16 baud, 2200 Hz wide spread spectrum
>> was very poor on UHF under Doppler spreading. Can you confirm this
>> with flutter tests like Jaak has done on
>> http://contestia.blogspot.com/p/pathsim_09.html
>>  ?
>>
>> 73, Skip KH6TY
>>
>> On 7/19/2010 9:42 PM, Tony wrote:
>>
>>> All,
>>>
>>> With all the attention ROS has been getting lately, I thought it
>>> would be interesting to see how the narrow mode compared to the wide
>>> version under the controlled environment of the HF path simulator.
>>> After a few hours of testing, it seems there's little difference
>>> between the two.
>>>
>>> The simulator indicated that they both had the same sensitivity
>>> (-15db) and essentially the same poor channel performance
>>> characteristics (see throughput samples below). In no case did one
>>> mode outperform the other to the point where it would make any real
>>> difference; both have the essentially the same wpm rate as well.
>>>
>>> These tests are not conclusive, but they do suggest that there may
>>> not be any real advantage in using the wide mode vs narrow under most
>>> circumstances. Of course, the simulator can only emulate the basic
>>> characteristics of the real HF channel so it would be interesting to
>>> hear from those who have compared the two on-air.
>>>
>>> Tony -K2MO
>>>
>>> 
>>>
>>> CCIR-520-2 POOR CHANNEL SIMULATIONS: -11DB SNR
>>>
>>>
>>> ROS 2250 / 16 baud
>>> the quick brown fox jumps over the lazy dog
>>> the quick brown fox jumps over the lazlµog
>>> Lghe quick brown fox jumps over the lazy dog
>>> the quccirown fox jumps over the lazy dog
>>> the quick brown fox jumps over the lazy dog
>>> Âe quick brown fox jumps over the lazy dog
>>> the quick brown fealoeumps ovahe lazEh/i
>>>
>>> ROS 500 / 16 baud
>>> the quick brown fox jumps over the lazy dog
>>> the quick brown fox jumps over the lazy dog
>>> the quick breFn fox juo3s over tes lazy dog
>>> the quæe t ´uls r?umps over the lazy dog
>>> the quick brown fox jumps over the lazy dog
>>> the quick brown f Á jumps over the lazy dog
>>> the quick brown fox jumps over the lazy dogQo
>>>
>>
>>
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>
>
> 




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[digitalradio] Re: directly modulate computer /thus eliminating transceiver audio input"

[IMR]

If only more software authours would provide their audio drive in stereo I/Q 
form it would make direct upconversion a real doddle.   If the signals were 
generated at baseband, even poor I/Q balance would not be too serious, as the 
image then lies on top of the wanted signal.

For narrow band modes, say no more than a couple of hundred Hz wide, a simple 
two opamp allpass network can be used to generate quadrature signals. 40dB 
isolation can be managed without too much effort.

http://www.g4jnt.com/IQConverters.htm

This is the soluition I use for generating linear 137 and 500kHz RF.
http://www.g4jnt.com/LFUpconv.pdf


Andy
G4JNT



--- In digitalradio@yahoogroups.com, "obrienaj"  wrote:
>
> "I am developing a 'modem' to directly modulate computer generated modes to 
> RF thus eliminating the requirement of using a transceiver audio input"
> 
> 
> Welcome to the group, tell us more.
> 
> Andy K3UK
>