IMPROVED BEEP ON BAD DATA FEATURE FOR POCSAG PAGING PROTOCOL (01-Sep-1997)
The current Beep on Bad Data feature will warn pager users if errored data is received, hut not if a page is terminated due to errors. To decide if a message has errors, an error detection algorithm is run on the POCSAG data blocks. If errors are found, the message is marked as errored. If two errored POCSAG blocks are received in a row, the page is terminated, but not marked as errored. The pager can not tell the difference between the trans- mitter turning off at the end of a page, and noise that causes two consecutive blocks to contain errors. In the latter case, a page will be truncated and not marked as errored.
0 M M-LA
Technical Developments
IMPROVED BEEP ON BAD DATA FEATURE FOR POCSAG PAGING PROTOCOL
by Ken Lerner and John Burgan
BACKGROUND
The current Beep on Bad Data feature will warn pager users if errored data is received, hut not if a page is terminated due to errors. To decide if a message has errors, an error detection algorithm is run on the POCSAG data blocks. If errors are found, the message is marked as errored. If two errored POCSAG blocks are received in a row, the page is terminated, but not marked as errored. The pager can not tell the difference between the trans- mitter turning off at the end of a page, and noise that causes two consecutive blocks to contain errors. In the latter case, a page will be truncated and not marked as errored.
SOLUTION
A message length field is added to the begin- ning of the page. This allows the pager to know in advance where the end of the page will be, so if the page is terminated early, the page can be marked as errored.
The page length indicator should be transmitted immediately after the pager's address, and before any data is sent~. The page length can be encoded as the first part of the page data, or as a separate POCSAG block that precedes the page data.
In the case of numeric pages, only 2 bits of data are required to describe the normal 4 POCSAG block maximum length that would normally be used for numeric pages. This could easily be encoded in the first "digit" position in the first numeric POCSAG data block (which contains 4 bits and could describe up to 16 blocks in length). See Figure 1. Another approach would be to use the function bits in the POCSAG address field. See Figure 2. These two function bits are only used on
pagers that are using "group" functions, "priority" functions, or multiple phone numbers assigned to a single pag...
Find More Documents Like This
Download this Disclosure
- a representative PDF of the primary disclosure file (contains all the relevant information for most users)
- the full disclosure ZIP file containing the primary disclosure, packaged metadata, and attachments (as appropriate)
