Loading ...
Sorry, an error occurred while loading the content.

Re: [linuxham] RTTY weak signal performance comparisons

Expand Messages
  • Steinar Aanesland
    Hi Martin I hope that I am not doing something wrong reposting this, but here Path Simulations test comparing RTTY to others modes. This was posted on
    Message 1 of 6 , Feb 2, 2009
    • 0 Attachment
      Hi Martin

      I hope that I am not doing something wrong reposting this, but here Path
      Simulations test comparing RTTY to others modes. This was posted on
      digitalradio@yahoogroups.com a while ago. As you can see , RTTY is not
      doing so well .

      73 de LA5VNA Steinar

      -------

      Digital Mode HF Path Simulations

      Complied by Anthony Bombardiere, K2MO

      dxdx@...

      Path Simulator by Moe Wheatley, AE4JY


      Digital mode Software

      Fldigi

      Jason

      MixW

      MMVari

      Multipsk

      WSJT

      _________________________________________________


      Baseline Sensitivity Test

      Minimum SNR

      A simulated direct path (no disturbance) was used to establish a
      baseline SNR for each mode. The minimum SNR was determined when all data
      (Pangram text)passed through the simulator without error.


      JT65(WSJT).......................-30db
      Jason Turbo (Fast)...............-25db
      PSKAM10..........................-20db
      PSK10............................-18db
      MFSK4............................-16db
      Contestia 500/32.................-15db
      DominoEX-4 ......................-15db
      FEC-31...........................-15db
      THROBX-4.........................-15db
      MFSK16...........................-14db
      Olivia 1000/32...................-14db
      THOR11...........................-14db
      RTTYM*...........................-13db
      Contestia 500/16.................-13db
      CW 20 WPM**......................-13db
      THOR16...........................-12db
      Olivia 500/16 ...................-12db
      MFSK31***........................-12db
      MT63 500Hz ......................-10db
      Olivia 500/8.....................-10db
      PSK31........................... -10db
      CHIP-64...........................-8db
      DominoEX-11.......................-8db
      MT63 1K...........................-8db
      Olivia 500/4..................... -8db
      PSK63.............................-7db
      Feld Hell.........................-7db
      CHIP-128..........................-5db
      RTTY 45...........................-5db
      PAX2..............................-2db
      HFPacket (300baud)................+1db
      *Intermittent "bug" with RTTYM MixW Software
      **Subjective; Morse speed dictates SNR
      ***MMVari software
      ______________________________________________



      Ionospheric Simulations

      Propagation simulators are often used to test the performance of HF
      communication systems. Although they cannot duplicate the infinite
      number of complex variations that take place within the ionosphere, they
      can mimic some of the fundamental characteristics of HF path distortion.

      The ionosphere is always in flux so conditions can change from one
      minute to the next. The ionospheric parameters of the simulator remain
      constant which makes for a more level playing field when comparing modes.

      The effects of Doppler and multipath are always present to some degree;
      even on quiet days. Modes that are less robust will start to show a
      decrease in throughput as the magnitude of the distortion increases.

      The simulations should help when choosing an alternative mode that's
      more likely to survive when conditions deteriorate.


      Simulation: High Latitude Moderate

      Path delay: 3ms

      Frequency spread: 10Hz

      SNR: -8db (weak signal)

      Mode Throughput
      Contestia 500/16.................100%
      CW 20 WPM........................100%
      MFSK16...........................100%
      MFSK31...........................100%
      Olivia 1000/32...................100%
      Olivia 500/16....................100%
      Olivia 500/8.....................100%
      RTTYM 500/32.....................100%
      Olivia 500/4......................90%
      Feld Hell*........................90%
      ThrobX-4..........................70%
      Chip-64.......................No Copy
      Chip-128......................No Copy
      DominoEX 4bd..................No Copy
      DominoEX 11bd.................No Copy
      FEC-31........................No Copy
      PSK31.........................No Copy
      Jason Turbo (fast)............No Copy
      PSK10.........................No Copy
      PSKAM10.......................No Copy
      PSK63.........................No Copy
      RTTY45........................No Copy
      THOR-11.......................No Copy
      THOR-16.......................No Copy
      MT63..........................No Copy

      SNR: +10db (Moderate Signal)

      Chip64..........................90%
      Chip-128**......................00
      Feld Hell*......................90%
      Olivia 500/4....................90%
      RTTY45..........................90%
      ThrobX-4........................70%
      DominoEX 4bd................No Copy
      DominoEX 11bd...............No Copy
      FEC-31......................No Copy
      PSK31.......................No Copy
      Jason Turbo(fast)...........No Copy
      PSK10.......................No Copy
      PSKAM10.....................No Copy
      PSK63.......................No Copy
      THOR-11.....................No Copy
      THOR-16.....................No Copy
      MT63........................No Copy

      *diffuse text - readable
      **Intermittent decode problem with Chip-128

      _______________________________________________________


      Simulation: High Latitude Disturbed

      Path delay: 7ms

      Frequency spread: 30Hz

      SNR: -3db (weak signal)


      Mode Throughput

      Contestia 500/16.................100%

      CW 20 WPM........................100%
      Olivia 1000/32...................100%
      Olivia 500/16....................100%
      Olivia 500/8.....................100%
      Olivia 500/4......................95%
      RTTYM**...........................95%
      MFSK31........................... 90%
      MFSK16............................75%
      RTTY..............................40%
      Chip-64...........................10%
      Chip-128**....................no copy
      DominoEX-4....................no copy
      FEC-31........................no copy
      Jason Turbo (Fa...............no copy
      MT631K........................no copy
      PSK10.........................no copy
      PSKAM10.......................no copy
      PSK31.........................no copy
      PSK63.........................no copy
      Thor-11.......................no copy
      ThrobX-4......................no copy
      Feld Hell....................Readable

      SNR: +10db (Moderate Signal)

      Olivia 500/4......................100%
      Feld Hell*.........................90%
      Chip64.............................75%
      Chip-128**.........................75%
      RTTY45.............................50%
      ThrobX-4.......................No Copy
      DominoEX 4bd...................No Copy
      DominoEX 11bd..................No Copy
      FEC-31.........................No Copy
      PSK31..........................No Copy
      Jason Turbo (fast..............No Copy
      PSK10..........................No Copy
      PSKAM10........................No Copy
      PSK63..........................No Copy
      THOR-11........................No Copy
      THOR-16........................No Copy
      MT63...........................No Copy

      * diffuse print - readable

      ** Intermittent decode problem Chip-128
      ________________________________________________________


      Simulation: Mid-Latitude Disturbed

      Path delay: 2ms

      Frequency spread: 1Hz

      SNR: -8db SNR (weak signal)



      Mode Throughput

      Contestia 500/16.................100%
      MFSK16...........................100%
      Olivia 1000/32...................100%
      Olivia 500/16....................100%
      Thor-11..........................100%
      Thor-16..........................100%
      CW 20 WPM.........................90%*
      DominoEX 4bd......................90%
      Feld Hell.........................90%
      MFSK31 ...........................90%
      MT63 1K...........................90%
      Olivia 500/8......................90%
      Olivia 500/4......................90%
      RTTYM 500/32......................90%
      ThrobX-4..........................90%
      DominoEX 11bd.....................80%
      FEC-31............................70%
      PSK31.............................70%
      PSK63.............................50%
      PSKAM10...........................50%
      Jason Turbo (Fast)................35%
      RTTY45............................20%
      PSK10.............................20
      Chip-64...........................20%
      Chip-128**.........................00

      SNR: +10db (Moderate Signal)

      DominoEX 11bd.....................100%
      Feld Hell*........................100%
      FEC-31............................100%
      MT63..............................100%
      Olivia 500/4......................100%
      THOR-11...........................100%
      THOR-16...........................100%
      ThrobX-4..........................100%
      SK63...............................95%
      Chip64.............................90%
      PSK31..............................90%
      PSKAM10............................90%
      RTTY45.............................90%
      DominoEX 4bd.......................90%
      Chip-128**..........................00
      Jason Turbo (fast).............No Copy
      PSK10..........................No Copy

      * diffuse print - readable

      ** Intermittent decode problem Chip-128
      ______________________________________________________________

      Simulation: Low-Latitude Disturbed

      Path Delay: 6ms

      Frequency Spread: 10Hz

      SNR: -8db SNR (weak signal)

      Mode Throughput

      Contestia 500/16................100%
      MFSK16..........................100%
      MFSK31..........................100%
      Olivia 1000/32..................100%
      Olivia 500/16...................100%
      RTTYM 500/32....................100%
      CW 20 WPM........................90%
      Olivia 500/8.....................90%
      Olivia 500/4.....................90%
      Throbx-4.........................70%
      Feld Hell.................Poor Copy*
      Chip-64......................No Copy
      Chip-128.....................No Copy
      DominoEX 4bd ................No Copy
      DominoEX 11bd................No Copy
      FEC-31.......................No Copy
      Jason Turbo (Fast)...........No Copy
      MT63 1k......................No Copy
      PSK10........................No Copy
      PSKAM10......................No Copy
      PSK31........................No Copy
      PSK63........................No Copy
      RTTY45.......................No Copy
      Thor-11bd....................No Copy
      Thor-16bd....................No Copy
      SNR: +10db (Moderate Signal)
      Olivia 500/4.....................100%
      Feld Hell........................90%*
      Chip64............................90%
      Chip-128.........................??**
      RTTY45............................70%
      ThrobX-4......................No Copy
      DominoEX 4bd..................No Copy
      DominoEX 11bd.................No Copy
      FEC-31........................No Copy
      PSK31.........................No Copy
      Jason Turbo (fast)............No Copy
      PSK10.........................No Copy
      PSKAM10.......................No Copy
      PSK63.........................No Copy
      THOR-11.......................No Copy
      THOR-16.......................No Copy
      MT63..........................No Copy

      * Characters diffuse difficult to read.

      ** Intermittent decode problem Chip-128

      __________________________________________________________



      NVIS

      Near Virtical Incidence Skywave

      NVIS waves penetrate deeper into the ionosphere
      than waves that are beamed at low angles. The
      increased interaction with the plasma tends to
      slow the wave down increasing the time-of-flight.
      NVIS sky waves can 'mix' with ground waves due to
      the close proximity of the stations. This causes
      internal timing issues for some digital modes as
      the two signals interact.

      Simulation: Mid-Latitude NVIS*

      Path Delay: 20ms*

      Frequency Spread: 1Hz

      SNR: +10db

      Mode Throughput

      Contestia 500/32.................100%
      CW 20 WPM........................100%
      MFSK16...........................100%
      MFSK31 (MMvari)..................100%
      MT63 1K..........................100%
      Olivia 1000/32...................100%
      Olivia 500/16....................100%
      RTTYM 500/32.....................100%
      THOR11...........................100%
      THOR16...........................100%
      Contestia 500/16..................95%
      Olivia 500/4..................... 95%
      DominoEX-4 .......................95%
      DominoEX-11.......................85%
      Feld Hell**.......................80%
      RTTY 45...........................80%
      Chip-64...........................75%
      DominoEX-22.......................60%
      THROBX-4..........................60%
      PSK31.............................10%
      PSK63.............................10%
      FEC-31............................nil
      PSKAM10...........................nil
      PSK10.............................nil

      ARQ Modes (Unproto)

      ALE400............................10%
      Pax...............................nil
      Pax-2.............................nil
      HFPacket (300baud)................nil
      HFPacket (300baud)................nil
      *Worse case scenario -- 20ms
      **Hellschreiber text ghosting - difficult to read

      __________________________________________________________


      ARQ Modes

      Minimum SNR (Direct Path no Ionospheric distortion)

      PAX (UNPROTO)...................-11db
      ALE400 (UNPROTO).................-8db
      PAX2 (Unproto)...................-7db
      HF Packet (300 baud Unproto).....+1db
      _______________________________________________


      Ionospheric Simulations

      Throughput SNR = complete Pangram decode

      *Indicates partial decode

      Partial decode criteria: => 50%

      Simulation: High Latitude Moderate

      Path delay: 3ms

      Frequency spread: 10Hz

      Mode Throughput

      ALE400 (Unproto).............-1db / -6db*
      PAX (Unproto)................-4db / -10db*
      PAX2 (Unproto)...............+2db / 0db*
      HF Packet (Unproto 300bd)......NO DECODE

      *Partial decode

      ___________________________________________________


      Simulation: High Latitude Disturbed

      Path delay: 7ms

      Frequency spread: 30Hz

      ALE400 (Unproto)......Incomplete / +2db*
      PAX (Unproto)..................NO DECODE
      PAX2 (Unproto).................NO DECODE
      HF Packet (Unproto 300bd)......NO DECODE
      ___________________________________________________

      Simulation: Mid-Latitude Disturbed

      Path delay: 2ms

      Frequency spread: 1Hz

      ALE400 (Unproto)...............-2db / -6db*
      PAX (Unproto)..................-4db / -10db*
      PAX2 (Unproto).................+1db / -2db*
      HF Packet (Unproto 300bd).........NO DECODE
      _____________________________________________________


      Simulation: Low-Latitude Disturbed

      Path Delay: 6ms

      Frequency Spread: 10Hz

      ALE400 (Unproto)................0db / -5db*
      PAX (Unproto)...................0db / -6db*
      PAX2 (Unproto)....................NO DECODE
      HF Packet (Unproto 300bd).........NO DECODE
      _________________________________________________________________

      RSID and Video I.D. Tests

      (MutliPSK Software by F6CTE)

      Minimum SNR (no Ionospheric distortion)
      RSID......... -25db
      Video ID.......-2db
      _____________________________________

      Ionospheric Simulaitons

      High-Latitude Moderate

      RSID............No Decode

      Video*.....Partial Decode

      * Diffuse text difficult to read regardless of SNR High-Latitude Disturbed

      RSID........No Decode

      Video*......No decode

      *Text completely diffuse

      Mid-Latitude Disturbed

      RSID........-25db

      Video....... +3db

      Low-Latitude Disturbed

      RSID...........no decode

      Video*....Partial decode

      * Diffuse text difficult to read
      __________________________________________________________

      WSJT Modes

      Minimum SNR (direct path - no ionospheric distortion)

      JT65A*...........-30db
      WSPR*............-30db
      JT6M.............-12db
      FSK441............-2db

      *On-air minimum SNR (approximate).

      Ionospheric Simulations

      High-latitude Moderate (-8db SNR)

      Mode Throughput

      JT6M.............100%
      JT65..........no copy
      WSPR..........no copy

      High-latitude Disturbed (-3db SNR)

      JT6M..............75%
      JT65..........no copy
      WSPR..........no copy

      Mid-latitude Disturbed (-8db SNR)

      JT6M.............100%
      JT65.............100%
      WSPR.............100%

      Low-latitude Disturbed (-8db SNR)

      JT6M.............100%
      JT65..........no copy
      WSPR..........no copy


      Doppler Tolerance

      JT65 / WSPR

      Both modes seem to have a low tolerance to the increased Doppler spread
      found on high and low latitude paths.In this test, the spread was
      increased until throughput was lost. Spread tolerance was roughly 1.5 Hz
      for WSPR and 3.5 Hz for JT65. A -20db SNR was used for this test since
      both modes are likely to be used for weak-signal work.

      Test #1

      Path delay: 1ms
      Doppler: 0.5 Hz (-20db SNR)

      Mode Throughput

      JT65..............100%
      WSPR..............100%

      Test #2

      Path delay: 1ms

      Doppler: 1 Hz (-20db SNR)

      JT65..............100%
      WSPR..............100%

      Test #3

      Path delay: 2ms
      Doppler: 2 Hz (-20db SNR)

      JT65..............100%
      WSPR...........no copy

      Test #4

      Path delay: 2ms
      Doppler: 3 Hz (-20db SNR)

      JT655..............100%
      WSPR............no copy

      Test #5

      Path delay: 2ms
      Doppler: 3.5 Hz (-20db SNR)

      JT655..............100%
      WSPR............no copy

      Test #6

      Path delay: 2ms
      Doppler: 4 Hz (-20db SNR)

      JT65............no copy
      WSPR............no copy
      _______________________________________________

      WSJT Mode Description

      FSK441: Intended for VHF/UHF high speed meteor scatter -- not suitable
      for HF.

      JT65: EME and other weak signal work (HF/VHF/UHF)

      JT6M: Specifically developed for 6 meter ion / meteor scatter.

      WSPR: Weak Signal Propagation Reporter (digital beacon).
    Your message has been successfully submitted and would be delivered to recipients shortly.