prob with nano

[Ian Thomas]

was recording a football match the nano was set at 19mbs mpg when i got home i found that the nano had only recorded 65mins when it should have been 85mins, have had this prob before but this time everytime i looked the nano was recording, never have this prob when recording on mov at whatever bit rate.

Any ideas please

[Alastair Traill]

Any "lost SRC" messages during the recording session?

[Ian Thomas]

hi Alastair

no that i noticed

[Andrew Stone]

For event recording I set the nanoFlash to be triggered by the record button on the unit in the event the operator hits the record/stop button on the camera.

[Dan Keaton]

Dear Ian,

How were you triggering the nanoFlash?

If you were triggering the nanoFlash via System|Trigger|Timecode (TC) or Timecode > Last TC, then the nanoFlash will record as long as your camera's timecode is incrementing.

If you camera stops incrementing timecode, the nanoFlash will stop recording.


What camera were you using?

Was it a tape based camera?

If so, did the tape run out at 65 minutes?

With my XL H1, with 63 minutes of tape, I get 65 minutes on one Panasonic Master Quality Tape.

With non-tape-based cameras, if the media in the camera runs out, then timecode will stop incrementing (if you are using Record Run timedcode).

[Ian Thomas]

hi Dan

Iam using the EX3 and the nano was set to record vi the camera record button and i was using sxs as back up and the nano is set to trigger timecode (tc)

Thanks
Ian

[Dan Keaton]

Dear Ian,

If the nanoFlash is set to System|Trigger|Timeccode (TC), you are set up to record on incrementing timecode and stop when timecode stops.

I feel that your camera may have stopped incrementing timecode at 65 minutes, thus stopping the nanoFlash.

[Ian Thomas]

Hi Dan

the camera recorded 84 mins to sxs cards which was the correct time

The only pauses in recording was if the ball went out for goal kick or if a player needed treatment

As i said before i didn't have time to be watching the nano lcd all the time but when i did it was working fine
this problem only seems to happen in MPG settings as i have filmed the match say at 35mbs MOV with no problems

Any other ideas

[Alastair Traill]

Hi Ian,
This is more of a comment than a reply, I have had the occasional “lost SRC” with my nF - EX3 combination. After reading your 30th October thread I looked at my SDI cables. The supplied cable was too long for my set-up and I snagged it on a branch tearing the cable from one connector. I shortened the cable and replaced both connectors with 50 ohm solder-type right-angle connectors. All vey neat and tidy as the cable is now only 8” long. Apparently I made mistakes in buying 50 ohm instead of 75 ohm and solder instead of crimp. I could add that my supplier only stocked 50 ohm and I can find nothing relevant to the subject in the nF manual.
I would happily buy 75 ohm cables and connectors but as “lost SRC” happen so rarely I am left wondering whether there might be some other problem as well. Under what conditions can I expect failures? I understand that 75 ohm cables are better for higher data rates but increasing the rate from my usual 100 mbits/s to 180 mbits/s did not produce a “lost SRC”.

[Dan Keaton]

Dear Alister,

Please forgive me, as I get a little technical.

Proper HD-SDI transmitting circuitry have a characteristic impedance, 75 Ohms.

In order for the power to flow freely and most efficiently, the connector must be 75 Ohms. Anything else will transmit the power less efficiently. And the cable must be 75 Ohms for the same reason.

Then the cable will have a characteristic impedance (the AC resistance to the flow of electricity).

Since the HD-SDI signal is a 1.485 Gigabits per second, it is a little like a radio wave.

If you have a signal flowing smoothly, a nice smooth wave, and the 75 Ohm cable meets a 50 Ohm connector, some of the energy flows into the connector, and some is reflected back into the cable.

Now, one has two waves, the one with the information, our signal, and another wave superimposed on this signal, this wave goes all of the way back to the source.

Every time the wave meets an impedance mismatch, it reflects back again creating another wave.

This works against the signal.

The receiver electronics has to extract the main signal from all of these extra waves.

If the receiver fails to do this correctly, then one gets a "Lost Source".

So, to help avoid this problem, we highly recommend using 75 Ohm connectors and cables.

And, if one gets “Lost Source” errors, replacing the cable would be the first step in attempting to diagnose and solve the problem.

[Alastair Traill]

Dear Dan,

Thanks, I don’t have any reason to doubt any of that, however I am puzzled by the fact that I only rarely get a “lost SRC” signal.

I would like to see a section along these lines in the nF manual. Unless you are in the know, one BNC connector looks very like another. As you pointed out in an earlier thread of Ian’s even Wikipedia got the distinction wrong. My component supplier was and probably still is unaware of the difference. I would not be surprised in the if other nF users have made the same mistake.

[Dan Keaton]

Dear Alister,

I have asked our team to update our manuals.

The first image is of a 50 Ohm BNC connector.

Please note the white ring that is on this connector.

The other two images are 75 Ohm connectors, they do not have this white ring.

50 Ohm connectors and cables have the potential to cause problems.

We advise against using them.

[Ian Thomas]

well i have ordered 2 new cables both 75 0hm but i would be surprised if on this occasion that is the problem, iam filming a xmas play thursday although it won't have the stop and starts the football match we will see what happens, thank god the sxs works ok

[Dan Keaton]

Dear Ian,

I agree, it may not be the cables.

However, eliminating the cables is a very logical first step.

We will be happy to evaluate your nanoFlash.

May I suggest that when you get the new cables, run some extensive tests, if you have time, and check if you have any problems.

If so, then we can test and repair your nanoFlash if appropriate.

[Cees van Kempen]

Originally Posted by Dan Keaton

Dear Alister,

I have asked our team to update our manuals.

The first image is of a 50 Ohm BNC connector.

Please note the white ring that is on this connector.

The other two images are 75 Ohm connectors, they do not have this white ring.

50 Ohm connectors and cables have the potential to cause problems.

We advise against using them.

I have a connector with the white ring and my supplier assures me it is 75 Ohm. According to him a white ring does not necessarily mean it is 50 Ohm.