Date   

FT4 curve increasing

Ham Radio
 

Lots of FT4 activity on 20 and 40 meters from this part of the country (Ottawa) since the COVID19 crisis.

Lots of DX on 20 as well  if you don’t mind using FT4. 

Checking 15 meters every day and nothing heard.

Lots of FT8 on 80 meters but little activity on FT4 ... strange.


Be safe!

 
73, Bernie,  VE3FWF


The Resurrection Day Olivia Digital Net - two more times, today. #Olivia

 

The Olivia Resurrection Day NET, on 14.107 dial, center 14.1085, 16/1000 - went well at the 1530 UTC net time. We had four additional stations, that checked in:
K3UK, KC4LZN, N1TYH, and, N7ZDR
This net will be called two more times, today.
Here are the proposed times:
+ 1930 UTC on 14.107 dial, center 14.1085, 16/1000
+ 2130 UTC on 14.107 dial, center 14.1085, 16/1000
Remember that we have a Facebook group:
Also, remember to subscribe to our email list, if you have not yet done so.
73 de Tomas, NW7US dit dit

https://QRZ.com/db/NW7US
Space weather and radio propagation editor for CQ Amateur Radio Magazine, and The Spectrum Monitor magazine. 
+ YouTube: https://YouTube.com/NW7US
+ Social Media:
    - Twitter:  @NW7US = https://Twitter.com/NW7US
    - Facebook (As NW7US):  https://fb.me/NW7US
    - Facebook (As Space Weather and Radio Propagation Page):  https://fb.me/spacewx.hfradio
    - Blog: https://blog.nw7us.us

..


Re: WIN 10 Standby mode , stopping programs running

Graham
 

Hybrid sleep .......
W10 standby is not a simple standby after a certain time - it's hybrid sleep (see Google) by default on a desktop, laptops different.  That time is user selectable.

If you just want to power off the screen for a while before sending it to sleep for example then it's Settings>Power & Sleep  You can also get into the detail under the Additional Settings link on that page.

Alan G0TLK


Re: Mystery JT65 signal

Patrick Lindecker
 

Hello Andy,

 

If KVASD (soft decoder) is ON, extract it to OFF. This decoder is very sensitive but introduce false decodes. The standard “hard decoder” has not this problem (although a false decode is still possible but very rare).

 

73

Patrick

 

De : main@digitalradio.groups.io [mailto:main@digitalradio.groups.io] De la part de Andrew OBrien
Envoyé : vendredi 10 avril 2020 15:08
À : main@digitalradio.groups.io
Objet : [digital-mode-radio] Mystery JT65 signal

 

Fron a ham on my WSJTX group.
Andy K3UK

<ha3pg@...>

7:14am

Hi everyone,



I struggle identifying a mysterious JT65 signal on the
30m band. I already asked this in other groups but no solution so far.

A few weeks ago I stumbled on a regular JT65 transmission on 10140.7kHz
transmitting every third minute. The message does not seem like coming
from ham, no callsigns but a cryptic string of characters, see this
short log excerpt:

20200408_1402 -21 -0.6  763 # KJIVVFULMOAI              .
20200408_1411 -21 -0.6  764 # KJIVMFULMQ00              .
20200408_1417 -21 -0.6  764 # KJIVMFULMQ05              .
20200408_1420 -23 -0.6  764 # KJIVKFULMQB0              .
20200408_1426 -19 -0.6  764 # KJIVDFULMR00              .
20200408_1429 -24 -0.6  764 # KJIVMFULMQAG              .
20200408_1505 -23 -0.6  765 # KJIVJFULMP00              .
20200408_1535 -21 -0.6  764 # KJIVJFULMP95              .
20200408_1541 -25 -0.6  764 # KJIVLFULMP00              .
20200408_1547 -22 -0.6  764 # KJIVKFULMP7F              .
20200408_1550 -26 -0.5  764 # KJIVQFULMO9H              .

This signal appears to be JT65, at least it can be decoded as one and
transmits every 3 minutes. Looks like a beacon or similar.

What we know so far, not in any particular order of importance:

- freq: 10140kHz +700Hz USB
- transmits 7/24 every third minute
- correct JT65 coding, can be decoded using WSJT-X or JTDX
- the message shows a pattern of

    KJIVxFULMxxx

where capitals are always the same while at places x varying

- carefully examining condx, appearing/disappearing of the sig,
coincidences to FT8 sigs shows probable location somewhere in AS Russia,
East EU, or maybe North EU, although at his stage needs further
listening, collecting of data and evaluation to narrow possible area

See a screenshot attached from yesterday evening. Yet a few wav files
can be downloaded as 9A5CW Patrick recorded two days ago:

https://drive.google.com/open?id=1-asTxJwq0nEhQJlCs0M6v6rYgjcqz9QC

I am curious to know if anyone else also noticed this transmission, has
additional details or willing to help me spotting the source.


Thank you, 73...  Sanyi, HA3PG




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Re: Mystery JT65 signal

Graham
 

Any of the  compressed format  systems ,  will  'always  produce ''valid''  out put , when  subjected to a  repeating  ''noise'' 
pattern , where  pre formatted  messages are  encountered, it becomes  ever more  ' realistic' 

Much merriment , is had, when  opera  responds to a  repeating , 'noise pattern [ usually a  keying attribute of a  'beacon kit' excited  transmitter' ] and go's on  to  print , what is perceived as  false  detections , only applies to  136 band , where  s/n levels  to  -45 dB are encountered ,  hence very low  spurious signals ,  cause  'havoc'  , once lodged in the  call  list , then other stations ,  similar respond ... catch22

I suspect, this is a  repeating  beacon , but not  JT system ,  intruder more  like ?

73-Graham
g0nbd


Mystery JT65 signal

Andrew OBrien
 

Fron a ham on my WSJTX group.
Andy K3UK

<ha3pg@...>
7:14am

Hi everyone,



I struggle identifying a mysterious JT65 signal on the
30m band. I already asked this in other groups but no solution so far.

A few weeks ago I stumbled on a regular JT65 transmission on 10140.7kHz
transmitting every third minute. The message does not seem like coming
from ham, no callsigns but a cryptic string of characters, see this
short log excerpt:

20200408_1402 -21 -0.6  763 # KJIVVFULMOAI              .
20200408_1411 -21 -0.6  764 # KJIVMFULMQ00              .
20200408_1417 -21 -0.6  764 # KJIVMFULMQ05              .
20200408_1420 -23 -0.6  764 # KJIVKFULMQB0              .
20200408_1426 -19 -0.6  764 # KJIVDFULMR00              .
20200408_1429 -24 -0.6  764 # KJIVMFULMQAG              .
20200408_1505 -23 -0.6  765 # KJIVJFULMP00              .
20200408_1535 -21 -0.6  764 # KJIVJFULMP95              .
20200408_1541 -25 -0.6  764 # KJIVLFULMP00              .
20200408_1547 -22 -0.6  764 # KJIVKFULMP7F              .
20200408_1550 -26 -0.5  764 # KJIVQFULMO9H              .

This signal appears to be JT65, at least it can be decoded as one and
transmits every 3 minutes. Looks like a beacon or similar.

What we know so far, not in any particular order of importance:

- freq: 10140kHz +700Hz USB
- transmits 7/24 every third minute
- correct JT65 coding, can be decoded using WSJT-X or JTDX
- the message shows a pattern of

    KJIVxFULMxxx

where capitals are always the same while at places x varying

- carefully examining condx, appearing/disappearing of the sig,
coincidences to FT8 sigs shows probable location somewhere in AS Russia,
East EU, or maybe North EU, although at his stage needs further
listening, collecting of data and evaluation to narrow possible area

See a screenshot attached from yesterday evening. Yet a few wav files
can be downloaded as 9A5CW Patrick recorded two days ago:

https://drive.google.com/open?id=1-asTxJwq0nEhQJlCs0M6v6rYgjcqz9QC

I am curious to know if anyone else also noticed this transmission, has
additional details or willing to help me spotting the source.


Thank you, 73...  Sanyi, HA3PG


WIN 10 Standby mode , stopping programs running

Graham
 

WIN 10 Standby mode , stopping programs running 

Previously, this was not  a issue ,   win-xp  and  7 , the  upgrade
to  win-10, apperese to of embodied a  pre-set  list of parameters 
ie,  access to  microphone, eliminated the ic7100 rx data feed 

Q-Is there a  setting, to  prevent a  program ,  ie,  data  mode ,  stopping, when the  pc 
enters , 'standby  mode,  ?

Previously,  the  video to the  vdu , may of stopped, but, the  program[s] 
continued running , attribute setting  may be ?



Tnx- Graham
g0nbd


Re: K3SIW , Sending Opera op32 on the lowFER band #opera #lowfer

Graham
 


k3SIW  ,spotted by NK9M

Assume  on the  LowFER band ,  

level  showing ~ -43 dB,  50 down from the  previous , 
1 watt  reduced to  10 uWatts ? 
all  correlation ,spot, but, time looks  good = good spots 

73-Graham

2020-04-09 02:58:46 K3SIW AA NK9M EN51UQ 0 136 -43 Op32__~43dB
2020-04-09 01:58:46 K3SIW AA NK9M EN51UQ 0 136 -43 Op32__~43dB
2020-04-09 00:58:46 K3SIW AA NK9M EN51UQ 0 136 -43 Op32__~43dB
2020-04-08 23:58:46 K3SIW AA NK9M EN51UQ 0 136 -44 Op32__~44dB
2020-04-08 22:58:46 K3SIW AA NK9M EN51UQ 0 136 -44 Op32__~44dB
2020-04-08 21:59:05 K3SIW AA NK9M EN51UQ 0 136 -43 Op32__~43dB
------------------------------------------------------------------------------------------------------------------------------------------------------------
2019-12-12 08:58:54 K3SIW AA NK9M EN51UQ 0 136 10 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_10dB
2019-12-12 07:58:54 K3SIW AA NK9M EN51UQ 0 136 9 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_9dB
2019-12-12 06:58:54 K3SIW AA NK9M EN51UQ 0 136 8 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_8dB
2019-12-12 05:58:55 K3SIW AA NK9M EN51UQ 0 136 7 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_7dB
2019-12-12 04:58:55 K3SIW AA NK9M EN51UQ 0 136 6 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_6dB
2019-12-12 03:58:54 K3SIW AA NK9M EN51UQ 0 136 10 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_10dB
2019-12-12 02:58:54 K3SIW AA NK9M EN51UQ 0 136 11 Op32_||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||_11d


New release of MULTIPSK (4.43) - P25 Phase 1 #Multipsk

Patrick Lindecker
 

New release of MULTIPSK (4.43) and Clock (1.11.9)

 

Pour les francophones: la version en français de ce message se trouve sur mon site (http://f6cte.free.fr). Il suffit de cliquer sur le lien "Principales modifications (courriel avertissant de la sortie de la nouvelle version)".


Hello to all Ham and SWL,

 

The new release of MultiPSK (4.43) is on my Web site (http://f6cte.free.fr/index_anglais.htm).
The mirror site is Earl's, N8KBR: https://www.paazig.net/f6cte/MULTIPSK_setup.exe

The MD5 signature of the downloaded MULTIPSK_setup.exe file to, possibly, check (with WinMD5 for example), that the downloading works without error, is equal to:

91a82da992983d78672aea610fb9d055

Multipsk associated to Clock are freeware programs but with functions submitted to a licence (by user key).

 

The main improvement of MULTIPSK 4.43 is the following:

 

Ham P25 Phase 1 decoding (but not the voice)

 

"P25" is the acronym for "APCO Project 25", for two different radio systems: "Phase 1" (used also by Hams) and the most recent "Phase 2" (not used by Hams). Only the "Phase 1" P25 mode is decoded by Multipsk.

It is used in VHF and in UHF. It is a mode for professionals but also used by amateurs (according to a precise organization). For Hams, it is spread in a world net by using, among other means, repeaters and Internet.

 

The amateur P25 communications are the sole object of the Multipsk decoding (professional communications are decoded but ignored). The P25 is considered as a "professional" mode by Multipsk (but the Ham decoding is not limited in time).

 

It is here only considered the data communication which summarizes to identifiers (callsigns).

Note: the voice communication decoding is excluded because it needs an IMBE Codec.

 

For Hams and SWL, the P25 signal can be received:

·                     either from the discriminator output of a classical VHF/UHF FM receiver via a direct connection to the PC sound card. However, the receiver must have a large reception bandwidth due to the high modulation speed,

·                     or with a SdR receiver (FunCube Dongle, RTL SDR,...) and directly demodulated by Multipsk. It is the simplest solution.

 

Here is the WEB address where you can know where all P25 repeaters are located, with their frequencies, for each country: https://www.repeaterbook.com/repeaters/niche/index.php?mode=P-25

 

This mode is in freeware, so without time limitation.

 

See general specifications below.

 

 

Note about translation of Multipsk.exe and Clock .exe:  the 4.42 version of Multipsk has been translated to Spanish by Joachin (EA4ZB), from French.

See: http://f6cte.free.fr/Translation_files.htm.

 

73

Patrick

 

Description of the P25 mode

Baud rate: 4800 (with 2 bits per symbol so 9600 bps)

 

Modulation : each double logic signal (dibit) directly modulates, through a raised cosine filter (to reduce the bandwidth needed), the VHF or UHF frequency in 4FSK (on about +/- 4.5 KHz). So this signal is received in base band after FM demodulation.

It is also used a "CQPSK" modulation, which is demodulated as C4FM.

 

Reception mode: FM

 

Shape of pulse : raised cosine filter

 

Bandwidth : about 9 KHz

 

Detection and synchronization code: yes on 48 bits.

 

Codes: several codes are used (Hamming, BCH, Golay, Reed-Solomon...)

 

Interleaving : no

 

Scrambling: no

 

Transmission

 

Each "superframe" is composed of the following data units: Header / Logical link 1 / Logical link 2 / Logical link 1 / Logical link 2 / Terminator (with or without Link control).

 

Each data unit is composed of a unique frame synchronization word on 48 bits, followed by a network identifier on 64 bits giving among other information the data unit type, and finally a piece of information depending on the data unit. The lenght and the coding of each data unit are different. The main piece of information is, of course, the digitalized voice.

 

The pieces of information that interest Multipsk are the ones contained in the Logical link 1 unit and in the Terminator with Link control unit, because they carry the IDs (Source + Talk Group or Destination + Source).

 

Note: contrary to DMR, this is not a TDMA system as it is managed only one transmission.

 

For about the interface between your PC and your transceiver, see the paper "HOW_TO_DO_DIRECT_DSTAR_BETWEEN_HAMs_Rev_A.pdf" located in the http://f6cte.free.fr/DSTAR.ZIP file, but taking into account only the reception part (no P25 transmission by Multipsk).

 

 




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ROS-HF 7 MHz ZS Net #ros

Graham
 

Checking the  ROS-HF user levels these days, on psk-map stat's 
Noticed an Interesting thing,

There is  a  7 MHz net , round south africa , but, ZS stations are all using
one of the older ros versions , not sure as to  why,  the latest version , provide's
the the  final  optimization , but each evolution came with  changes to  coding 
and the  modem , as one compliments the  other ..
Thus  coding ,  6-9-0  is not compatible with the new ,

It would be  possible to  monitor , using  web-sdr's ,

73-Graham
g0nbd

ROS v6.7.3+CAT/Rptr V1.4 1 IZ8STM

ROS v6.7.3/Rptr V1.4 2 IT9KYA, IZ8STM

ROS v6.9.0+CAT/Rptr V1.4 2 ZS6DPL, ZR6PC

ROS v6.9.0/Rptr V1.4 14 ZR6PC, ZR6EJH, ZS6BV, ZS4BC, ZS3P/4, ZS6GAX, ZS5UA, ZS2DRS, ZR6JAN, ZS6ADY, ZS6APB, ZS3P, ZS3PG, ZR5EE

ROS v6.9.7/Rptr V1.4 1 ZS6ADR

ROS v7.1.3/Rptr V1.4 1 LZ1XK

ROS v7.4.0+CAT/Rptr V1.6 254

ROS v7.4.0/Rptr V1.6 342


Re: Signs of the FT8 curve flattening ?

Andrew OBrien
 

I even saw this 

16:26:26 UTC QPSK125           802 Hz

Not often you hear someone using QPSK, and then 125 .


Among today's RSID hits 

16:49 KZ1O  CONTESTI 14073483
16:30 W5OTR  CONTESTI 14073483
16:29 N7ESU  PSK 14072202
16:15 N7RI  PSK 14072859
16:14 N7ESU  PSK 14072859
16:03 KG7D  PSK 14072267
15:43 N4UM  OLIVIA 14072977
15:34 KD5LPB  OLIVIA 14072767
14:18 K5TED  MFSK 14072854
13:37 WA5IEK  OLIVIA 14072886
13:23 W5OTR  CONTESTI 14073166
13:20 NR4A  OLIVIA 14072498
12:56 KD5LPB  OLIVIA 14072498
03:35 ZL1WN  OLIVIA 14072487
03:32 K7TPN  OLIVIA 14072487
03:18 zl1wn  OLIVIA 14072487
02:42 zl1wn  OLIVIA 14072487
02:41 KM6NFS  OLIVIA 14072487
02:38 ZL1WN  OLIVIA 14072487
01:44 W5ERX  OLIVIA 14072132
00:45 AC6P  OLIVIA 14072003
00:07 K0DXV  OLIVIA 14073101



Andy K3UK


Re: Opera QSO party running on 7038

Graham
 

Long skip , would of been the description in the past ?
most spots  1000  mile  + list ,last 7 days , unique
contacts ,  couple of -27 db listed, that would put op1 at
-24 and op05 -21 , which ~ system limit 

R3D-262 using web-sdr , as opera is  single tone and self  synchronising 
the audio processing [ tone elimination]  and  transit delay ,in the web , 
is not relevant , to performance 

73-Graham

2020-03-29 14:57:37 RX3DHR KO94KS R3D-262/RA0 PN78NM 6.140kmt  7.038 -26 Op2__~26dB
2020-04-03 15:07:03 RX3DHR KO94KS R3D-262/R0C PN78NM 6.140 7.038 -22 Op2_||||||||_~22dB
2020-04-03 15:16:18 RX3DHR KO94KS R3D-262/R9U NO33OS 3.077 7.038 -13 Op2_||||||||||||||||||||||||||_~13dB
2020-04-03 17:51:34 R3KEE KO91OH G0NBD IO83LK 2.835 7.038 -18 Op2_||||||||||||||||_~18dB
2020-04-03 17:46:49 G0NBD IO83LK R3KEE KO91OH 2.835 7.038 -22 Op2_||||||||_~22dB
2020-03-29 17:13:38 RX3DHR KO94KS G4MDH IO91BN 2.700 7.038 -20 Op2_||||||||||||_~20dB
2020-04-02 19:57:32 RX3DHR KO94KS G0NBD IO83LK 2.696 7.038 -20 Op2_||||||||||||_~20dB
2020-04-02 19:51:21 G0NBD IO83LK RX3DHR KO94KS 2.696 7.038 -17 Op2_||||||||||||||||_~18dB
2020-03-29 15:27:29 OH3FZQ KP11QL SV8RV KM07KS 2.642 7.038 -22 Op2_||||||||_~22dB
2020-04-03 17:46:49 G0NBD IO83LK SV8RV KM07KS 2.526 7.038 -24 Op2_||||_~24dB
2020-03-28 16:00:24 RX3DHR KO94KS SV8RV KM07KS 2.328 7.038 -17 Op2_||||||||||||||||||_~17dB
2020-04-03 17:39:00 R3KEE KO91OH SV8RV KM07KS 2.081 7.038 -22 Op2_||||||_~23dB
2020-03-29 16:04:48 RU2F KO04FR SV8RV KM07KS 1.886 7.038 -22 Op2_||||||_~23dB
2020-03-29 17:03:43 OH3FZQ KP11QL G4MDH IO91BN 1.882 7.038 -17 Op2_||||||||||||||||||_~17dB
2020-03-29 17:07:15 G4MDH IO91BN OH3FZQ KP11QL 1.882 7.038 -9 Op2_||||||||||||||||||||||||||||||||||_~9dB
2020-03-29 16:04:47 RU2F KO04FR RX3DHR KO94KS 1.178 7.038 -18 Op2_||||||||||||||_~19dB
2020-03-29 16:10:58 RX3DHR KO94KS RU2F KO04FR 1.178 7.038 -11 Op2_||||||||||||||||||||||||||||_~12dB
2020-03-29 14:24:36 OH3FZQ KP11QL RX3DHR KO94KS 1.172 7.038 -16 Op2_||||||||||||||||||_~17dB
2020-03-29 14:29:12 RX3DHR KO94KS OH3FZQ KP11QL 1.172 7.038 -7 Op2_||||||||||||||||||||||||||||||||||||||_~7dB
2020-03-29 16:04:47 RU2F KO04FR OH3FZQ KP11QL 770 7.038 -5 Op2_||||||||||||||||||||||||||||||||||||||||||_~5dB
2020-03-29 16:08:29 OH3FZQ KP11QL RU2F KO04FR 770 7.038 -14 Op2_||||||||||||||||||||||||_~14dB
2020-04-02 20:03:49 G0NBD IO83LK G4MDH IO91BN 223 7.038 -25 Op2_||_~25dB


Re: Signs of the FT8 curve flattening ?

Andrew OBrien
 

Some RSID TX hits I detected  while parked around 14071 , courtesy of Multipsk software 

18:35 KI5UH  PSK 14071541
18:26 2D0P  PSK 14071541
18:25 OA4CN  PSK 14071546
18:16 2D0PEY  PSK 14071546
16:50 AD0XB  OLIVIA 14071600
15:52 KC3FL  PSK 14071723
15:35 KC3FL  PSK 14071742
02:19 N0FPH  THOR 14072235
02:16 zl1wn  THOR 14072235
01:59 zl1wn  THOR 14072240
01:35 zl1wn  THOR 14072245
01:33 ZL1WN  THOR 14072245
01:19 zl1t  THOR 14072245
01:18 zl1wn  THOR 14072245
22:41 NW7US  OLIVIA 14072466
22:30 K4ZMR  OLIVIA 14072498
22:21 NW7US  OLIVIA 14072498
22:16 WB4QOJ  OLIVIA 14072504
22:04 NW7US  OLIVIA 14072498
22:01 K4ZMR  OLIVIA 14072509
21:53 N1CL  OLIVIA 14072509
21:52 NR4A  OLIVIA 14072509
21:05 EA7EZ  OLIVIA 14072520
20:49 NR4A  OLIVIA 14072520
20:43 NV1O  OLIVIA 14072525
20:33 NR4A  OLIVIA 14072525
20:29 EA7EZ  OLIVIA 14072723
20:22 NW7US  OLIVIA 14056433
ReporterInitialize Success


Re: Signals on 7.070 +1500-3000hz

Andrew OBrien
 

I have you heard this since?

Andy K3UK


Signs of the FT8 curve flattening ?

Andrew OBrien
 

I like working FT8 from time to time but lament the decline in the use of other digital modes on HF.  Lately however, I have seen what appears to be an increase in Olivia, Thor 8, and MFSK16 .  Perhaps with many hams staying home, they are looking for more conversational modes.  I had a nice QSO with Ross ZL1WN using Thor 8 on 20m late yesterday  (my evening).  The modes did well.


Andy K3UK 


Re: Signals on 7.070 +1500-3000hz

Graham
 

Not the  VARA modem apparently , 
looks like a  arq  system ,  with the  
short mid frame ?


Signals on 7.070 +1500-3000hz

David Miller
 

I heard some strange signals tonight, about 1.5kHz wide and sharp. I've never heard anything like it before.
Any idea of what this may have been ?, 28 Mar ~ 0240z



Harmonics in audio Tx drive / side bands / Gray Noise

Graham
 

Posted to the  RSGB tech group 
By G3PLX

Makes a  very valid point , surrounding  harmonics in TX audio  drive , whilst  using  SSB transmitter for  data  
level clipping is not the  holy grail  of  clean signals , applicable to  C / D & E pa's etc  , where say the  tones are  1500 hz , then the  harmonic falls  out of the  pass band, but,  for  systems  , using  a  wide  spread of tones , then harmonics from the  low 'set's can be in band . the phase disturbance exists  with or without limiting ,

73-Graham

In reply to  previous  posts  ..

Let me try to explain it better.  Say I have a 1 kHz tone with a second harmonic at 10%, going into a balanced modulator at 9 MHz, The output of that will be the two main F1+/- F2 components at 9001 and 8999, with two more at 9002 and 8998 at -20dB.  Let's select only the upper sideband with a filter, leaving one big signal at 9001 and a smaller one at 9002 20dB down.

Think of what this looks like on a phasor display.  The main signal is a dot rotating in a circle of radius 1.0 around the origen and the small signal is a dot rotating in a circle of radius 0.1 around that.  Not easy to visualise, so mentally de-spin the display so the main dot is stationary and it's easy then to see that the combined signal looks like a dot moving in a 0.1 radius circle around a point at a radius of 1.  The combined signal is varying in amplitude between 0.9 and 1.1, and ALSO swinging in phase by +/-0.1 radian (+/-5.7 degrees).

Remove the AM component by hard-limiting the signal (through a class C power amplifier) and the resulting signal is constant amplitude but the phase modulation remains.  The output spectrum will be a carrier at 9001kHz with phase modulation sidebands 1 kHz either side at approximately -26dB.   What was a single spurious tone at 9002 kHz at -20dB with a linear power amplifier, has become a pair of spurious tones at 9000 and 9002 at -26dB, if we remove the AM component with a saturated power amplifier.

So hard limiting the RF output of an SSB transmitter fed with a distorted audio tone, does not clean up the resulting distortion on the RF output.   It IS important to ensure that either (a) the audio tone generator is a pure sine wave or (b) that it's second harmonic lies outside the SSB filter passband.  This will be true regardless of how the tone is keyed, whether FSK or two alternating on/off tones or one tone keyed on and off.

73
Peter G3PLX


Olivia is partying #Olivia

Andrew OBrien
 

For the next few days I will be QRZ most of the day 1200-2359 UTC on 14107.5  ( 14106 dial ) Using Olivia 16/1000 with RSID. 

Andy K3UK (FN02,  New York)


Opera QSO party running on 7038

Graham
 

Opera QSO party running on 7038 

WQ2H  Running over the  last week , with  5  and  10  watts  
on 7028 Op02 , as well  as 1836  Op04 
7 puting  in some  good  ''qrp''   dx  at the  moment , 

73-Graham
g0nbd

So far ,  making over to US east coast  
........................................................................................................Kmt 
2020-03-20 19:22:49 EA2B IN91MP WQ2H FN32XV 5.667 7.038 -18 Op2_||||||||||||||||_~18dB
2020-03-19 21:00:38 G4MDH IO91BN WQ2H FN32XV 5.176 7.038 -23 Op2_||||||_~23dB
2020-03-17 22:59:08 G0NBD IO83LK WQ2H FN32XV 5.039 1.836 -30 Op4__~30dB

US to  EU
2020-03-20 21:11:09 WQ2H FN32XV EA2B IN91MP 5.667 7.038 -24 Op2_||_~25dB
2020-03-19 20:29:54 WQ2H AA G0NBD IO83LK 0 7.038 -25 Op2_||_~25dB
2020-03-19 19:39:32 WQ2H FN32XV G4MDH IO91BN 5.176 7.038 -23 Op2_||||||_~23dB

Last 24  Hrs 

RX3DHR R3D-262/RA0 40m OPERA 6140 km 15:27:57
EA2B WQ2H 40m OPERA 5667 km 20:48:53
WQ2H G4MDH 40m OPERA 3217 miles 20:56:25
WQ2H G0NBD 40m OPERA 3132 miles 21:09:06
G0NBD WQ2H 40m OPERA 5040 km 21:04:01
EA2B RX3DHR 40m OPERA 3235 km 20:48:53
RX3DHR EA2B 40m OPERA 3234 km 20:30:47
R3KCC G0NBD 40m OPERA 3014 km 19:03:40
R3KCC G4MDH 40m OPERA 2994 km 19:03:41
RX3DHR G4MDH 40m OPERA 2700 km 21:16:24
G0NBD RX3DHR 40m OPERA 2696 km 20:17:31
RX3DHR G0NBD 40m OPERA 2695 km 20:20:16
G0NBD SV8RV 40m OPERA 2525 km 18:06:13
RX3DHR SV8RV 40m OPERA 2325 km 21:03:49
R3KCC SV8RV 40m OPERA 2242 km 18:22:05
EA2B SV8RV 40m OPERA 1912 km 20:42:39
G0NBD EA2B 40m OPERA 1319 km 20:04:58
EA2B G4MDH 40m OPERA 1104 km 20:42:38
G4MDH G4MDH 40m OPERA 2 km 17:48:25


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