LMH1297: Signal loss due to pathological signal on the LMH1297EVM

Hiroshi Okada

Prodigy 10 points

Part Number: LMH1297

We are facing signal loss when 12G pathological signals are used with TI LMH1297EVM.

Signal loss occurs once every 2-3 hours in EQ mode.

No signal loss has occurred with the colorbar signal.

I think it's due to the out of sync of the CDR.

Do you have any idea to solve this problem?

The conditions of the evaluation as follows

Signal Generator : FOR A ESG-4100

Multi Waveform Monitor : LEADER LV 5400

SDI_IO Input Cable : CANARE L5.5CUHD

Length 2m EQ_GAIN Value : 3

3m EQ_GAIN Value : 3

30m EQ_GAIN Value : 9

All No Signal occurs

OUTPUT : OUT0

SDI_OUT

All No Signal occurs

Rerards,

H.Okada

over 2 years ago

0 Nasser Mohammadi over 2 years ago

TI__Guru* 88835 points

Greetings:

1). Is this EQ pathological?

2). Please confirm you SDI_OUT enabled?

3). Also, you have tested this at different cable lengths and it is not dependent on the cable length?

4). Is Leader the only generator you have used ? Video frame format does not influences the result?

Regards ,,Nasser

0 Hiroshi Okada over 2 years ago in reply to Nasser Mohammadi

Prodigy 10 points

Dear Nasser

Thank you for your reply.

1). Is this EQ pathological?

=> EQ mode and pathological.

2). Please confirm you SDI_OUT enabled?

=>SDI_OUT enabled

3). Also, you have tested this at different cable lengths and it is not dependent on the cable length?

=>It occurs on cables of all lengths.　Signal loss occurs momentarily.

4). Is Leader the only generator you have used ? Video frame format does not influences the result?

=>I use generator:FORA and receiver:LEADER.　Signal loss occurs only for Pathological signals.

Best regards, H.Okada

0 Nasser Mohammadi over 2 years ago in reply to Hiroshi Okada

TI__Guru* 88835 points

Greeting Okada-San,

Do you see this issue if SDI_OUT is disabled?

Regards ,, Nasser

0 Hiroshi Okada over 2 years ago in reply to Nasser Mohammadi

Prodigy 10 points

Dear Nasser

Do you see this issue if SDI_OUT is disabled?

=>Yes, This issue also occurs when SDI_OUT is disabled.

Signal loss occurs momentarily even if only Loop-thru OUTPUT using SDI_OUT is monitored.

Best regards, H.Okada

0 Nasser Mohammadi over 2 years ago in reply to Hiroshi Okada

TI__Guru* 88835 points

Greetings,

I am running out of ideas here.

Device was characterized and passed 1E-12 BER using PRBS10 - similar to color bar. However, it was not characterized using pathological pattern.

Regards ,,nasser

0 Hiroshi Okada over 2 years ago in reply to Nasser Mohammadi

Prodigy 10 points

Dear Nasser

Does it mean that signal loss cannot be eliminated with a 12G pathological signal?

Do you have any countermeasures?

EQ changes, CDR settings, etc.

Best regards, H.Okada

0 Nasser Mohammadi over 2 years ago in reply to Hiroshi Okada

TI__Guru* 88835 points

Greetings Okada-San,

This device was not characterized for long term test with pathological pattern. So what you are seeing could indeed be real. However, since device was not characterized under this condition, we cannot claim and meet this requirement.

Regards ,,Nasser

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LMH1297: Signal loss due to pathological signal on the LMH1297EVM