I would like to ask about TVG on the GP1871f. I know it is a pre-filter and it alters the received echoes permanently so I would like to know if there is a known relation with depth. For example, I see that at 60m the TVG values that do not alter the bottom echoes are 0..5 maybe 6. After that the bottom starts to faint. Is there a table that points to the max TVG according to bottom depth ?
TVG on GP1971f
- Thread starter asyrop
- Start date
asyrop,
I know that you have a good understanding on Time Varied Gain (TVG). I just want to explain to other people who might be reading this and want an explanation.
Echoes are displayed directly on the fish finder screen, the size of the displayed echo from the same school of fish may change with distance, making it difficult to judge the actual size of that school of fish. To overcome this inconvenience, TVG compensates for propagation loss of sound in water, where the amplification of echoes on short range are suppressed and then gradually increased as range increases.
Similar targets are displayed targets of the same size, regardless of target depth irrespective of the ranges to them. The TVG also functions to suppress any unwanted echoes and noise which appears within a certain range area on the fish finder screen.
The adjustment for TVG on the GP1871F/GP1971F uses a scale from 0-9 depending on range depth. I do not know of any table that shows TVG levels according to any bottom depth. Again, this can all depend on noise, other echoes, water depth, water temperature, or water salinity. Anything that may impact the echo sounder's beam.
- Deep Blue :think
I know that you have a good understanding on Time Varied Gain (TVG). I just want to explain to other people who might be reading this and want an explanation.
Echoes are displayed directly on the fish finder screen, the size of the displayed echo from the same school of fish may change with distance, making it difficult to judge the actual size of that school of fish. To overcome this inconvenience, TVG compensates for propagation loss of sound in water, where the amplification of echoes on short range are suppressed and then gradually increased as range increases.
Similar targets are displayed targets of the same size, regardless of target depth irrespective of the ranges to them. The TVG also functions to suppress any unwanted echoes and noise which appears within a certain range area on the fish finder screen.
The adjustment for TVG on the GP1871F/GP1971F uses a scale from 0-9 depending on range depth. I do not know of any table that shows TVG levels according to any bottom depth. Again, this can all depend on noise, other echoes, water depth, water temperature, or water salinity. Anything that may impact the echo sounder's beam.
- Deep Blue :think
M
Magnetron
Guest
Great explanation Deep Blue! :cool
The FCV1900 manual describes TVG this way,
I'm not sure if this further assists in understanding the properties of this setting. :sail
- Maggy
The FCV1900 manual describes TVG this way,
I'm not sure if this further assists in understanding the properties of this setting. :sail
- Maggy
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