DS280DF810: some problem in eye scan while using DS280DF810

Zhanpeng Li

Part Number: DS280DF810
Other Parts Discussed in Thread: SIGCONARCHITECT

Hi team,

this is brandon. one of my customer is using our DS280DF810 in their optical module. we have some question in eye scan.

1) through our datasheet and guideline of DS280DF810, we have finish the scan of left one. but we don't know how the scan the middle one? can you provide with some guideline?

2) Can you provide us with the document below?

Brandon.

over 5 years ago

0 Nasser Mohammadi over 5 years ago

TI__Guru* 93670 points

Hi Brandon,

1). Middle eye is eye hit density. In this case, we are taking derivatives of the eye hits in first step. Then these result are normalized and based on the normalized result it is decided whether there is a hit or not.

2). Calculation you highlighted is related to taking derivatives of the eye hit as i noted above.

3). Do you have SigconArchitect GUI? You can use this GUI with customer board to capture eye hit density.

4). Please refer to the below presentation discussing eye scan below. This provides more details:

https://training.ti.com/reconstruct-eye-diagram-raw-data

Regards,, Nasser

0 Zhanpeng Li over 5 years ago in reply to Nasser Mohammadi

TI__Intellectual 2140 points

Hi Nasser,

Sorry to bother. i may have more question:

1)Customer got the eye based on demo data in SigconArchitect GUI, but found that the scatter of eye is bad.

left eye is based on Demo 's Density data; the right one is based on Density data through raw data;

The information I got in accordance with the second step of the instructional video is drawn directly by the difference between the vertical data, but I don’t understand how step 3 and step 4 filter the scattered part, can you provide a specific analytical formula Detailed demo documentation.

in step3,It is said to be obtained by filtering the maximum hit point of the waveform of step 2. According to my understanding, the waveform obtained by step 2 is a group of delta values. If you filter on this basis, it cannot be achieved.If step2 is to obtain a rough waveform line outline, find the maximum hit point value in the raw data to filter under this outline, but it still cannot filter out the scattered part of the middle part.

2) in SigconArchitect GUI, in eye hit Density , what is the relationship between color and data? can you provide with an reference data?

3)Can you help to confirm whether the DS280DF810 can be set to reduce power consumption, currently we only use 2 channels.

Brandon.

0 Nasser Mohammadi over 5 years ago in reply to Zhanpeng Li

TI__Guru* 93670 points

Hi Brandon,

1). Due to the limited sampling of the incoming signal done by the state machine, there could be some scattered hits. Or hits that are by themselves. These are not real and need to be cleaned up. Therefor during post processing these should be taken out or cleaned up.

2). Based on number of hits or normalized hits then different color codes are used to show the intensity of occurrence of signal coming through. Normally highest rate of occurrence or highest number of hits corresponds to blue. Or black is no hit.

3). You can force CDR reset to the unused channels to reduce power consumption.

Regards,, nasser