Topic: sdhc speed

[bobxxx]

Does anyone know what the record speed is for the 798?(in record mode)?. I see a lot of different sd card capacities being used but not much mention of class types( 1 thru 10) or read write speeds.Will a 16 Gig sdhc card work the same if it were a class 2 vs a class 10 ?
Thank You
Bob

[LocDown]

I would get the fastest card you can get if you plan on doing sonar recordings.

[newkid4si]

I have been using SanDisk Extreme cards rated at 30MS/s for recording and have been very satisfied.
Just purchased two new SanDisk Ultra cards for the camera and they are now rated at 30MB/s.
Someone said the Extreme is now up to 45MB/s.
I agree with LocDown in using as fast as you can afford.

       Mike

[sonar2000]

Good post. And you are so right in advertising today. Manufactures can say just about any thing they want. No truth to advertising any more..
SanDisk seems to be the accepted card for sonar in HB units. Others have had success with brand "X" but SanDisk has had no complaints that I know of.
Problems arise in the speed of the unit (record) and the speed of the card. Not sure all are on the same page yet.

Chuck

[Fay]

I agree  the "SanDisk Extreme" seem to be great cards.     Fay

[bobxxx]

I just bought a "16 Gig Extreme Pro SDHC uhs-1 CARD" for $37 on sale from best buy with a read write speed of 95 MB/S. I guess I won't know how much $ I wasted until I find out the record speed of my HB 798
CI HD SI Combo.
Bob

[Humminbird_Greg]

Bob,
I don’t know that there is a clean answer to that as I’ve asked this before.  Basically I was told that they read/write “as fast as they can”.  It really depends on what else the unit is busy doing at the same time it is reading/writing to the memory card, but I doubt that would be in the 95MB/s speed!

[sonar2000]

While a particular component may be capable of a certain speed, it is tied to a processor and a bus. The program running the processor sets the priorities and processing tasks. So depending on the CPU type and cost .. read/write speeds may vary from component capability.   And vary from other units as the CPU's may operate differently.

In fact some are single thread while other may multi-task. Priorities (interrupts) may cause instructions to act differently accordingly to what is processing at the time..

Remember that sonar units are computers now and not hardware only...

Chuck

 

[bobxxx]

ok,guys,
Thanks for the comebacks.
Bob

[Jim Jack]

Well to start with you can not get 95M/s unless you have a device that supports the UHS spec (to 104M/s). I venture a guess that HB's do not support this. Looking through my archives an hour long worth of recording is between 360M and 560M.

To make the math easy lets round to 600M per hour, that would be 10M per minute and 166K per second at a steady continuous write.
I also would venture a guess that HB's does not have steady continuous write. This means that even at 100X of steady continuous write average you only get to 16.6M per second.

In conclusion I highly doubt that any HB is sd card write speed bound with anything class 4 and above. Back in the old days of class 1 and 2 sd cards it is possible that HBs were sd card write speed bound. You only wasted between 10-20 bucks, compared with a class 6 card, hey might as well buy class 10.

[sonar2000]

Jim our 1197 is using 6mb cards and we get well over an hour of recordings..
You are correct in that the unit does not continuously write to the card. It is in bursts.
chuck

[Jim Jack]

Chuck,
Little confuse about the point of your reply.

Even a 2Gig card will hold over 3hrs of recording at 600M per hour.

6M is 36 seconds of recording time and I do not believe HB queues up that much for each write cycle.

I'd love to know what the bus will handle and how much of that is enabled.

[sonar2000]

Jim sorry for the confusion. I just can't type today.  We use a 2gig card not a 6m. I think my 1 cell brain and the finger typing are not in sync. Kind of like HB recording mode cpu and memory  .....
I agree with you that it would be nice to know the bus speed, (as a techi) but in reality we find that 20 to 30 minutes recordings will produce enough information for several searchs and then review if nothing obvious.
Now for waypointing for fishermen I just dont know. We use another brand for navigation so I cant compare. And search is different than fishing..
Thanks for calling attention to the typing error. It makes a lot of difference in 6m to 2 gig..

Chuck

[Rickard]

Hi,
 
I have some strange experiences with memory cards with different r/w capacities. I have found there are wider recording gaps with faster cards, especially with a UHS-1 card, than with a slower card like a speedclass 6, 20 MB/s SDHC card. But there is another factor, recording with the 50/83 kHz downward channel on or off. Wide recording gaps are typical when the 50/83 kHz channel is turned off. When 50/83 kHz is on display scroll speed is lower and the recording gaps are more frequent, but these gaps are so narrow they don't do much harm to the image. The widest recording gaps I have seen were about 3 feet wide which definitely destroys the image of e.g. a wreck. I have seen reports on gaps with other and newer units than my 981 model, so I think this is some kind of basic architecture issue with Humminbird sonar systems. My 981 has done well for several years and I hesitate to upgrade until there is a guarantee for no more recording gaps.
 
Rickard

[sonar2000]

We have experienced gaps in recordings during searchs which is why we run multiple recordings over the same area. Just in case the first skipped the object. Of course our objects are small as in body size and gaps can cause a false report of nothing found.
So searchers, if the first does not show a target run it again...and as I have said in the past, run from different angles. The HB is capable of sounding the target...you just have to make it work for you.
That is why many hours of operating this unit is important. The eye has to look at the returns and see the gap when it occurs..
External viewers of recording are important. You will see more than the playback provides.
Chuck

[Jim Jack]

I have found that any recording over about 35 mins long seems to have gaps. I'm one of the beta testers for Navionics Sonar Charts and have been scrutinizing my records like I have not done in the past. Remembering the fishing trips and what I was doing while recording it seems that snapshots, waypoint marking/cursor use, and settings changes all have a negative impact on recording. I will be doing some testing to confirm this.

 

[sonar2000]

Great, be sure to share your experience and finding with us. Generally we find that recordings (sonar) over 30 minutes seems to be bulky and unwieldy. Also it does seem more gaps on a longer record. We usually go for about 20 minutes..
Glad you are testing on the team.  Keep us up dated.

Chuck