Methods and apparatus for error rate estimation

• US 9,661,350 B2
• Filed: 02/12/2016
• Issued: 05/23/2017
• Est. Priority Date: 01/27/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Whitby-Strevens, Colin
• Primary Examiner(s): FILE, ERIN M
• Application Number:
  US15/043,252
• Publication Number:
  US 20160249070A1
• Time in Patent Office: 466 Days
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder

Abstract

Methods and apparatus for estimating received error rates. In one embodiment, the estimation of received error rates is conducted in relation to a bus interface such as a high-speed High-Definition Multimedia Interface (HDMI) interface, and the method utilizes corrupted symbols that violate TMDS symbol rules, the corrupted symbols being easily detected and counted. In one exemplary implementation, a symbol error rate (SER) can be estimated from the number of detected invalid symbols. The SER can be used to diagnose the performance of the HDMI interface, and optionally as a basis for selecting or implementing corrective action(s).

Claims

1. An apparatus for estimating received symbol error rates, the apparatus comprising:

an interface operating in accordance with a digital display interface standard, the interface configured to receive a plurality of encoded symbols from an upstream device; and

a processing device in operative communication with the interface, the processing device being configured to;

determine an operational mode for the apparatus;

receive a plurality of encoded symbols during the operational mode;

detect one or more symbol errors associated with the received plurality of encoded symbols;

when a first invalid error symbol has been detected within the received plurality of encoded symbols, increment an error count; and

estimate a total number of symbol errors, based upon the incremented error count.

2. The apparatus of claim 1, wherein the operational mode comprises one of:

(1) a control period mode;

(2) a preamble reception mode;

(3) a guard band reception mode;

(4) a data island mode; and

(5) a video data mode.

3. The apparatus of claim 2, wherein during the control period mode, the only valid symbols are control symbols and preamble symbols.

4. The apparatus of claim 2, wherein during the preamble reception mode, the only valid symbols are preamble symbols and guard band symbols.

5. The apparatus of claim 2, wherein during the guard band reception mode, the only valid symbols are guard band symbols, video data and data island data.

6. The apparatus of claim 2, wherein during the data island mode, the only valid symbols are data island data, guard band symbols, and control symbols.

7. The apparatus of claim 2, wherein during the video data mode, the only valid symbols are video data and control symbols.

8. The apparatus of claim 1, wherein the processing device in operative communication with the interface, is further configured to:

responsive to detection of a given symbol, transition from the operational mode to a second operational mode.

9. The apparatus of claim 8, wherein the processing device in operative communication with the interface, is further configured to:

enter a loose checking state upon detection of an invalid symbol.

10. The apparatus of claim 9, wherein the loose checking state ensures that a disparity mismatch between the upstream device and the apparatus does not trigger an excessive amount of error counts.

11. The apparatus of claim 10, wherein the processing device in operative communication with the interface, is further configured to:

upon entering the loose checking state, leave the loose checking state at a predetermined later time.

12. The apparatus of claim 11, wherein the predetermined later time comprises the end of a scan line.

13. A method for estimating received symbol error rates in an apparatus that operates according to a digital display interface standard, comprising:

determining an operational mode for the apparatus;

receiving a plurality of encoded symbols during the operational mode;

detecting one or more symbol errors associated with the received plurality of encoded symbols;

when a first invalid error symbol has been detected within the received plurality of encoded symbols, incrementing an error count; and

estimating a total number of symbol errors, based on the incremented error count.

14. The method of claim 13, wherein the operational mode comprises a control period mode and the method further comprises:

comparing at least a portion of the received encoded symbols against a table;

wherein the only valid symbols for the compared portion of the received encoded symbols are control symbols and preamble symbols.

15. The method of claim 14, further comprising:

receiving a given symbol; and

transitioning from the control period mode to a data period mode in response to receipt of the given symbol.

16. The method of claim 15, further comprising entering a loose checking state upon detection of an invalid symbol.

17. The method of claim 16, further comprising leaving the loose checking state at a predetermined later time subsequent to entering the loose checking state.

18. The method of claim 17, wherein the act of leaving the loose checking state occurs upon reaching the end of a scan line.

19. A user device for estimating received symbol error rates, the user device comprising:

a visual display;

an interface operating in accordance with a digital display interface standard, the interface configured to receive a plurality of encoded symbols from an upstream device and transmit a plurality of content resultant from the received plurality of encoded symbols to the visual display; and

a processing device in operative communication with the interface, the processing device being configured to;

determine an operational mode for data received via the interface;

receive a plurality of encoded symbols during the operational mode;

detect one or more symbol errors associated with the received plurality of encoded symbols;

when a first invalid error symbol has been detected within the received plurality of encoded symbols, increment an error count; and

estimate a total number of symbol errors, based upon the incremented error count.

20. The user device of claim 19, wherein the digital display interface standard comprises a High-Definition Multimedia Interface (HDMI) standard.