fcv 587 tx rate and pulse length

[Anonymous]

when we lower the tx rate does the pulse length changes ?

 

[Snips]

Normally the PL doesn't change with the TX rate, only with range. However when my 587 returns from a field test I will put my scope on the output to confirm.

Snips

 

[Anonymous]

thank you for the answer
regards
Ibrahim

 

[Snips]

Ibrahim,
I confirmed that the pulse length on the FCV-587 doesn't change if the TX rate is changed.

Snips

 

[spooled1]

Gidday Snips,
Can you please explain how the Pulse Length changes according to Range and how returns might show up on the screen at different ranges based on those Pulse Lengths. I'm having trouble getting my head around this concept.

The other day I drift fished in 100m with the range set to 80m and 15m shift. The returns were totally perfect on the P66. Then, when I got out to 280m I got good seabed returns on 50hz but struggled to see fish no matter what ranges or shifts I played with on both 50 and 200hz. When I dropped my TX Rate by about 30% and set my TX power to high, I recall a change on screen but not sure if it was the setting or something else - My buddy on another boat was only 80m away at the time. He has a 587 and I think I may have read some of his interference. What are your thoughts?

 

[Snips]

Spooled1,
When you change the TX rate you also are changing the sounder screen advance rate. This is because the screen advance is based off of the TX rate. I am going to use some round numbers to try to simplify this. Fishing in 100m, TX rate of 10 and a screen advance of 1/1 it will take 1 minute for the picture to shift from right to left. If you are fishing in 300m, TX rate of 10 and 1/1 it will take 3 minutes. Now if you are still in 300m and you slow down the TX rate to 3 it may take 9 minutes for the picture to shift from right to left. This will make all your targets look very compressed. Remember I used round numbers in my example but hopefully that explains it. Personally I don't recommend ever slowing the TX rate.

Snips

 

[spooled1]

Gidday Again Snips - And sorry for the hijack!!!
I hope you can clarify something:

You said, fishing in 100m, TX rate of 10 and a screen advance of 1/1 will take 1 minute for the picture to shift from right to left and that pic advance will compress/enlarge the size of returns over time.

SO…In the context of ocean currents at a depth of 100m: A 1/1 screen advance speed is perfect for an average drift speed where the current runs at 3.6km/h coz the returns coincide with 'real time' as the picture advances across the screen on a speed per minute basis. On days where there’s a slow current of e.g. 1.8km/h, does this mean that a 1/2 speed screen advance will display the same type of, 'real time'. Then, on days where the current is running at 7.2km/h, would a faster 2/1 speed represent. 'real time''?

Or is my logic backwards - should I speed up pic advance in slow currents and slow it down in fast currents and then decide whether or not to change the advance speed in order to compress/enlarge.

 

[Snips]

Spooled1,
There are many ways to tweak a sounder display. Personally I also use a 1/1 screen advance anchored or doing 30 knots. You can simulate what you are talking about (at the dock) by putting sounder in the demo mode and going through the different screen advance rates.

Snips