FT8 Shootout

A comparison of FT8 decodes using different radios.

Abstract:

This project is an experiment to find out what settings and which of the models of transceivers we own is better for FT8 decoding.  We will count the number of decodes on each pass using the same antenna through a splitter.

Questions we will attempt to answer:  Is the $3000 IC-7610 worth the extra money over the $1000 IC-7300?  Is the $4000 Flexradio 6600?   How does AGC affect the number of stations decoded?  Should gain be set high to allow the weak stations a chance, or should it be set low to keep the strong stations from overloading the input?

Given:

Decoding is done in the computer application (WSJT-X v2.1.2) not the radio.  All models are direct sampling sdr’s.

Expectations:

Preconceived notions are that the more expensive radios will perform better.

Results: 

Test 1 – 7610 vs 7300 number of decodes per pass

7610     vs    7300

32                 36

33                 32

27                 29

28                 26

26                 25

36                 36

26                 27

Comment: Sometimes one wins. Sometimes the other. Sometimes they tie.  It’s a toss up.

Test 2 – SNR of same stations on each radio (callsign suffix shown)

7610    vs     7300

KV    +6        +4

LXD  -20      -20

ENN -21      -21

ON   +17      +16

Comment: There is more compression with strong signals by the 7300 .  Thus one would conclude there is slightly more dynamic range on the 7610.

Test 3 – Flex  vs   7300 number of decodes per pass, congested band

Flex    vs    7300

33                 33

31                 32

36                 35

30                 31

35                 36

36                  35

Comment: It’s a toss up.

Test 4 – Flex  vs   7300 number of decodes per pass, dead band

Flex    vs    7300

2                    2

2                    2

2                    2

3                    3

2                    2

Comment: Identical

Test 5 – SNR of same stations on each radio

MRB  -18       -19

JCN    -11       -10

RW     0         +1

PCC    -12      -12

Comment: Toss up.

Conclusion:  No substantive difference in the number of decodes among the three radios tested.  There are vast differences in features that may affect other modes or user experience but the  difference is minimal as measured by the yardstick of FT8 decode counts.

Notes:  It was found that the highest number of decodes was always with the rf gain as high as possible just short of the point of overload.  Strong stations were always decoded but if the rf gain was reduced weak stations disappeared.  It was also found that the best setting for AGC was FAST.  Other settings, including the setting recommended in the WSJT-X User Guide of AGC OFF, reduced the number of decodes.

Caution

Regard with caution any count of 36.  JTAlert was used as a counting tool and it only counts up to 36.  There could have been more than 36 in a pass and the extras were not counted.

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