Topics

AMTOR?


Andrew J. O'Brien <obrienaj@...>
 

I have not heard an AMTOR signal in ages, has AMTOR become extinct?

Andy KB2EOQ


Nick Fedoseev <nf@...>
 

Hello Andrew,

Friday, May 12, 2000, you wrote:

Andrew> I have not heard an AMTOR signal in ages, has AMTOR become extinct?

I heard AMTOR twice last year :-)



Best regards,
Nick mailto:nf@...


Les Warriner <leswa7ham@...>
 

Like CW?
.
.
.At 04:26 PM 05/12/2000 +0300, you wrote:

Hello Andrew,

Friday, May 12, 2000, you wrote:

Andrew> I have not heard an AMTOR signal in ages, has AMTOR become extinct?

I heard AMTOR twice last year :-)



Best regards,
Nick mailto:nf@...



------------------------------------------------------------------------
There's still time to order Calyx & Corolla flowers for mom.
These fresh and elegant bouquets are available for delivery
by Mother's Day. To order, please visit
http://click.egroups.com/1/4103/0/_/_/_/958139033/
------------------------------------------------------------------------

To unsubscribe from this group, send an email to:
digitalradio-unsubscribe@...



Nick Fedoseev <nf@...>
 

Hello Les,

Friday, May 12, 2000, you wrote:

Les> Like CW?

No, I heard CW much more often in the region of 14060..14112 :
- beacons on 14100,
- CWIDs anywhere,
- CW QSOs, mainly during CW contests

:-)




Andrew> I have not heard an AMTOR signal in ages, has AMTOR become extinct?

I heard AMTOR twice last year :-)


Best regards,
Nick mailto:nf@...


Andrew OBrien
 

Ha!  As we start a new decade, here is our first post to this email group from the year 2000!

Andy K3UK (ex KB2EOQ) 


Graham
 

I still  have the  pk232-mbx  , wired  up  , but  I  doubt the  bands are  in 
any condition to  make  contact ,  used to  take  200/ 250  watts to  work the  usa
east coast on  7  

Though,  interestingly , intrems of  a  ARQ   qso  , the   latest  version 
of the  VARA Hf modem  is now  MFSK  in the  lower  speed  ranges 
and coupled to a  'CHAT'  module , provides , 'traditional  qso'  

Unregistered, the  modem  is limited to  170 bauds  and  MFSK
only ,  being phase  cont ,  can be used  with  qrp   class  E/D 
systems , has excellent  low  s/n signal functionality , much lower
than amtor , more like  olivia ***

A work-round is to   un-register ,  ie  just enter a   'wrong key'
this  locks the  modem  and you  have a  simple  mfsk
chat mode  , with  full  ARQ ,   the  new  MONITOR 
function , provides off air  text  recovery , there is  no 
FEC mode  as such . 

Re entering  a valid key , restores functions ,   its not needed
to  un-register , only if the  TX is  none linear ie QRP etc 

*** Olivia has  phase component in the modulation 
scheam , and requires linear TX/RX path 

73-Graham
G0nbd


Andrew OBrien
 

Interesting Graham.  I'll have to update my VARA software.
Andy K3UK


Graham
 

Ok Andy 

A lot work  went into the  vara modem,  I'm  sure there  are  many  more uses , that  just sending  e-mail and files ,  
The   'wrong key , is not an  official  mod,  but,  it occured to  me, that  it opens up other possibilities , by  retaining the 
phase continuous mfsk  modem 

The  'chat'  module  , handels  the  Tx/Rx control , with listings  of  Rigs and  com-port options ,  allowing  for  new equipment to  be  added  , without updating the  main modem,  which ,  causes knock on effects for  some time  .. 

Direct keyboard  entry is via the  chat module , it also  has a  file  attachment facility  as well , 
The tx and rx text is  scrolled  in the  chat app , with  indication , the  text  has been  'delivered' 

Sort of  half / full duplex ,as the  link  direction , is under the  control of the modem, 
inputted text   is  simply  forwarded , as and when the  qsb allows , from each side of the  link ..
arq  / speed changes remain  as normal , these is  no  . Tx/Rx  selection ,once the  link is
established ,  flow  commences 

Novel  feature, files may be  simply  delivered to a station , much the  same as a  mail box
connect  to  , send ,  disconnect ,  the  file is  stored at  the  remote , 

The  monitor  function is  provided  on the  main modem  app , selecting   monitor,  the   ''mid section'' ,  speed/s/n display 
changes to  'scrolling text' display , this  could be utilised  in a net  situation,  providing off  air  copy  of other  stations ,  it appears to  incorporate  the  ARQ function ,  providing 'just'  plain  text 

I would  suspect,  where olivia is  used as qso  mode,   vara [ locked or open]  would  provide  faster  and  reliable  qso's 
though  at 2k fixed  b/w , once  link is  established , the  change over / re-lock  time ., [determined by the  FEC  and  syn  time] , is  eliminated , as the  modem is  'locked' 

Be interesting to hear  how  it  performs ,  ''out of water'' ,  

Digital voice ?

73-Graham 
g0nbd 


David Walker
 

hI,

I am happy to make amtor connections if anyone is interested.

I put out calls occasionally on 20m around 14082 and 14107.5 but i haven't had any connections.

Regards

Dave
VK2NA
SECAL VKNA


Graham
 

I dont think its a  mode  / use problem,  I used to  have  regular contacts with the  USA  east  on 7  MHz using  amtor , long back, 
running  round  240 watts  carrier power , one guy even  asked me 'which state liverpool was in'  , unexpected  dx ..

the new  generation  of  data modes , reduced the  power needs to something like  25  watts  , a good  + 10 db gain , to  do the  same thing 

That was when the  bands where in  good  condition , I do  know from  tests  on 476 KHz , the  latest vara HF modem is  as  sensitive 
if not  more so, than the slowest  olivia mode , but  many times  faster and provides a  amtor like  fast  turn  round  qso  , using the  chat  module , interesting  test with  station  200  miles  south  of me , on MF  

73 -Graham
g0nbd


Rick Muething
 

Graham/All,

Digital modes have evolved much over the past 20 years.  There is however a basic underlying limit (Initially described by AT&T engineer Claude Shannon  in a landmark 1948 paper that proposed (which has now been proven) there is a basic limit to how much information can be sent within a given channel with a given amount of noise... and this is limited to the Energy per bit (Watts x symbol length divided by bits/symbol) divided by the Noise (No).  This is true whether we are talking about Deep space probes or HF Ionospheric propagation.  What has changed is better DSP (digital signal processing) and error correcting codes that allow us to more closely approach that limit.  Excellent examples today on HF are VARA (2300 Hz or 500 Hz bw) and Pactor 4 (1900 Hz bw). Pactor 4 is one of the first amateur mode to use dynamic channel equalization that improves its throughput dramatically in multi-path propagation common on HF.  If interested in some comparisons  of popular digital modes on HF and VHF/UHF see the write-up at  https://winlink.org/content/ionos_simulator

73,

Rick Muething, KN6KB


On 10/27/2020 6:33 PM, Graham wrote:
I dont think its a  mode  / use problem,  I used to  have  regular contacts with the  USA  east  on 7  MHz using  amtor , long back, 
running  round  240 watts  carrier power , one guy even  asked me 'which state liverpool was in'  , unexpected  dx ..

the new  generation  of  data modes , reduced the  power needs to something like  25  watts  , a good  + 10 db gain , to  do the  same thing 

That was when the  bands where in  good  condition , I do  know from  tests  on 476 KHz , the  latest vara HF modem is  as  sensitive 
if not  more so, than the slowest  olivia mode , but  many times  faster and provides a  amtor like  fast  turn  round  qso  , using the  chat  module , interesting  test with  station  200  miles  south  of me , on MF  

73 -Graham
g0nbd