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The ADVISOR™ Message Receiver

POCSAG Coding Rules

Advisor Pager

and suggestions for programming capcodes

Individual Codes
Group Codes
Mail Drop Code

TABLE OF CONTENTS
POCSAG Coding Rules
Group Calls - General
Pager group call
Terminal group call
Information Services
Invalid POCSAG codes
Code Assignment Strategy
Source Identification
Function Codes for Information Services
Message Indication Types
Mail Drop
Paging Terminal and Mail Drops
Message Storage
Group Calls
Group Call Capcode Assignment
Capcode Assignment Illustration
POCSAG frames

ADVISOR™ Message Receiver - POCSAG Coding Rules

The Motorola ADVISOR™ is capable of supporting 1, 2, 3, or 4 POCSAG codes.

Here are the rules when requiring two POCSAG codes:

Here are the rules when requiring three POCSAG codes:

Here are the rules when requiring four POCSAG codes:

Formula to find the frame number:

Example: Code A= 2017670÷8= 252208.75
or
Code B= 1657614÷8= 207201.75
.75 x=6
Frame=6

More Examples

FrameRemainderMath example
0none0 x 8 = 0
1.125.125 x 8 = 1
2.25.25 x 8 = 2
3.375.375 x 8 = 3
4.5.5 x 8 = 4
5.625.625 x 8 = 5
6.75.75 x 8 = 6
7.875.875 x 8 = 7

Group Calls - General
There are two general methods of performing "group call." When several users are assigned to a common group so that they can all be paged in one transmission, this is called Pager group call. All the pagers in the group must have a common capcode. This type of group call is only possible with pagers that can have more than one capcode because of the requirement for both individual and group message reception. Since most modern pagers can be programmed with several different capcodes, this is now the most widely used type of group call.

Another type of group call that is not used very much anymore, is the Terminal group call. In this type of group call, the individual capcodes within the group are unrelated to each other. This group call is initiated by sending one message to a subscriber record, or a "pilot number" in the paging terminal. The paging terminal contains all the members of that group stored in its memory. The terminal then sends the message to each subscriber in the group, one after another. This results in separate transmissions to each subscriber and is very expensive in terms of air time. Not all paging terminals can do a group call of this type, and some paging companies do not offer this type of group call to their customers although their terminal has the capability. There are two reasons for this: 1) This type of group call is wasteful of air time since the group call message must be sent separately to each member of the group, and 2) some older paging terminals slow down considerably while they search the whole data base to locate all the members of the group. This can also create a delay between the time the first pager in the group and the last pager, receive their copy of the message.

Information Services
Subscription to information services is a very promising application of radio paging. Information services may include news headlines, weather forecasts, sports scores, and financial information. It is important to understand how to properly assign group call or Mail Drop codes for this type of service for the following reasons:

The POCSAG code makes it easy to order pagers evenly distributed across the eight frames of a batch. The eight frames are numbered zero through seven (0-1-2 3-4-5-6-7). If pagers for individual messaging use are programmed sequentially, they will be equally distributed, because each time the capcode is incremented by one, the next code is assigned to the next higher frame until frame seven is reached. After frame seven, the assignment jumps back to frame zero. This can be easily seen in the POCSAG frame tables that begin on page below.

* Invalid POCSAG codes:0000000to0000007
2007664to2007671
2045056to2045063
2097144andgreater

Code Assignment Strategy
Since this is a paper about the ADVISOR pager, it will continue to be used as an example while different ideas are presented about pager code assignments. These same ideas should be applicable to other model pagers by taking into consideration their different specifications especially those relating to code and memory capacity.

Source Identification
It was pointed-out previously that an ADVISOR pager can be programmed with up to four cap codes. Page one of this paper explained how these codes must be related to each other. Each POCSAG code has four "sub-codes" which are called, Function Codes, Addresses, or Source Identifiers. All three of these names are commonly used to describe the same thing. These codes were first used to show the source of a tone-only page. By assigning different numbers to the paging terminal and then giving out these access numbers to certain people, it was possible know the source when receiving a page. For example you could give one number to your boss, another to your wife, and another to your secretary. When your (tone-only) pager beeps, a distinct sound would show which number at the paging terminal was called and therefore the source (or origin) of the call.

It would work something like this: Your boss wants to get in contact with you, s/he would dial 364-3779. The public telephone network would switch the call to the carrier's paging terminal and relay the last four digits "3779" to the paging terminal. The paging terminal would use the incoming "3779" digits to look up your subscriber record. This record would show that your tone-only pager has capcode "1234567" with function code number one activated. The paging terminal would send your code over the correct radio channel. IF you are within the radio coverage area, IF your pager is turned on, IF your battery is good, and IF there are no strong electrical noises in the vicinity, then your pager will beep. Key to identifying the source is that there are four different sounding beeps. The best way to show this is with another example:

Telephone NumberCapcode(Address)
Source-code
Audible Alert
364-37791234567 1beeeep beeeep
364-37801234567 2bep-beeep bep-beeep
364-37811234567 3beeep-bep beeep-bep
364-37821234567 4beep-beep-beep-beep

So, if you hear the sound associated with source-code (or address) number one, you know it is your boss calling, the sound for source-code two means it is your wife, and the sound for source code three could mean for you to call your secretary.

That is how the source code got started - to show the source of the call to a tone only pager. With a numeric or an alphanumeric display pager the source-code is not so useful since the telephone number of the calling party is displayed on the pager, or better-yet, a complete alphanumeric message tells you everything you need to know.

Function Codes for Information Services
For Information Services we can make very valuable use of this extra part of the capcode as an "address code." Since the ADVISOR has a capacity of four capcodes and each capcode has four Addresses, (also called source-codes or function codes) then we can have up to sixteen different Addresses in the pager. This is great for Information Services and is exactly what we do when we set up the "Mail Drop" feature in the ADVISOR.

Message Indication Types
Messages sent to the ADVISOR can be selected as individual, group, or Mail Drop. Individual messages, also called personal messages, are shown on the first line of the message-status screen. Group messages are indicated by a special group prompt at the end of the message. Individual messages can be shown with the address number if the Show-Source option is selected. Mail Drop messages are displayed on the second line of the message-status screen.

Mail Drop
Any of the four address codes can be selected as Mail Drop. Mail-Drop messages differ from private messages as follows:

Mail Drop addresses work like they were separate capcodes. If one of the Mail Drop addresses is being used for showing the currency exchange rate, it will always have the latest information in the same message location or "slot". Imagine how confusing it would be if the exchange rate was sent out as an individual message. It would be very difficult to find which of the many messages in memory was the latest quotation. It would be necessary to read all the messages and look at the time stamp of each to determine what the latest exchange rate was. Fortunately, that is not how it works. As each new Mail Drop message comes into the pager, it replaces (erases) the previous message. All the subscriber needs to do is read the message in the "slot" on the pager screen designated for the currency exchange rate. It will always be the latest one and will always be in the same place.

Paging Terminal and Mail Drops
Each of the 16 possible addresses in the ADVISOR must be treated as a separate capcode in the paging terminal. This can easily be accomplished in most paging terminals. It is simply a matter of setting up four subscriber records for each capcode and programming each record for a different address (function code or source code). Please refer to the Capcode Assignment Illustration below. If the carrier is offering four information services on one capcode and a subscriber only wants to pay for three of them, then the ADVISOR can be programmed with an "X" in that slot, making that address inactive.

Message Storage
The ADVISOR can store up to 20 personal messages (individual or group) that are located on the first line of the message-status screen. Newer (or unread) messages are located on the right side of the first line; older messages are located on the left side of the first line. The pager can store up to 16 Mail Drop messages that are located on the second line of the message-status. (If all 16 are used there would be no address available for personal messages.) Also, up to ten messages can be stored in the history dump file and up to ten messages in the personal message file. A single alphanumeric message can be up to 2000 characters in length, depending on system capability.

Group Calls
Group calls are very effective for firemen, security personnel, and medical response teams. A cardiac-arrest-response team might be made up of several doctors and nurses each having an individual code for private messages and a group-call code for alerting them all at the same time that someone has had a heart attack.

For a large-scale Information Service operation, Group Calls probably do not offer enough flexibility for long-term growth. It would be better to allocate code "C" and/or code "D" for Information Services. This will cause a minor reduction in the pager's battery life (approximately 30%), due to its operation in two different frames, but will make the assignment of the different Information Services easier.

Another example: the table on the following page shows how to select a group call code and then assign ten pagers with individual codes to the group. Each pager will have an individual code for private messaging, and a group call code for messages of common interest to the whole group. This table illustrates the rule that each individual code in the group must skip eight codes in the sequence so that all the codes will be in the same frame. Another table follows on the next page, showing the same codes which were selected, but illustrating them grouped together.

CAPCODEFRAMEASSIGNMENTCAPCODEFRAMEASSIGNMENT
11111117Group Call11111531 
11111120 11111542 
11111131 11111553 
11111142 11111564 
11111153 11111575 
11111164 11111586 
11111175 11111597Individual Call
11111186 11111600 
11111197Individual Call11111611 
11111200 11111622 
11111211 11111633 
11111222 11111644 
11111233 11111655 
11111244 11111666 
11111255 11111677Individual Call
11111266 11111680 
11111277Individual Call11111691 
11111280 11111702 
11111291 11111713 
11111302 11111724 
11111313 11111735 
11111324 11111746 
11111335 11111757Individual Call
11111346 11111760 
11111357Individual Call11111771 
11111360 11111782 
11111371 11111793 
11111382 11111804 
11111393 11111815 
11111404 11111826 
11111415 11111837Individual Call
11111426 11111840 
11111437Individual Call 11111851 
11111440 11111862 
11111451 11111873 
11111462 11111884 
11111473 11111895 
11111484 11111906 
11111495 11111917Individual Call
11111506 11111920 
11111517Individual Call11111931 
11111520 11111942 

 

Group Call Capcode Assignment Summary
CAPCODEFRAMEASSIGNMENTCODE "A"CODE "B"
11111117Group Call  
11111197Individual Call11111191111111
11111277Individual Call11111271111111
11111357Individual Call11111351111111
11111437Individual Call11111431111111
11111517Individual Call11111511111111
11111597Individual Call11111591111111
11111677Individual Call11111671111111
11111757Individual Call11111751111111
11111837Individual Call11111831111111
11111917Individual Call11111911111111

This is an illustration of the ten codes selected from above. There are ten individual codes and one common group-call code. The assignment of capcodes to Code "A" and Code "B" in the pager is also shown. All the codes are in the same POCSAG frame ( i.e. frame 7 ).

Please note that according to the Coding Rules on page one, a pager programmed according to this example cannot have Codes "C" and "D" added later. Let's review the rules for four POCSAG codes in the ADVISOR:

So if there is any possibility that these users would want to subscribe to Information Services in the future, it would be better if their codes were in a frame less than frame seven. This, however, would not be a major problem since a pager can be easily reprogrammed at any time. If a carrier should want to offer eight different Information Services, on the following page there is an example of one way to program ADVISOR pagers for Individual, Group, and Information Services. An ADVISOR can only operate in two frames.

POCSAG batches image

Capcode Assignment Illustration

Advisor Addresses Image

POCSAG frames according to the last 3 digits of the 7-digit capcode

Frame
0
Frame
1
Frame
2
Frame
3
Frame
4
Frame
5
Frame
6
Frame
7
000001002003004005006007
008009010011012013014015
016017018019020021022023
024025026027028029030031
032033034035036037038039
040041042043044045046047
048049050051052053054055
056057058059060061062063
064065066067068069070071
072073074075076077078079
080081082083084085086087
088089090091092093094095
096097098099100101102103
104105106107108109110111
112113114115116117118119
120121122123124125126127
128129130131132133134135
136137138139140141142143
144145146147148149150151
152153154155156157158159
160161162163164165166167
168169170171172173174175
176177178179180181182183
184185186187188189190191
192193194195196197198199
200201202203204205206207
208209210211212213214215
216217218219220221222223
224225226227228229230231
232233234235236237238239
240241242243244245246247
248249250251252253254255
256257258259260261262263
264265266267268269270271
272273274275276277278279
280281282283284285286287
288289290291292293294295
296297298299300301302303
304305306307308309310311
312313314315316317318319
320321322323324325326327
328329330331332333334335
336337338339340341342343
344345346347348349350351
352353354355356357358359
360361362363364365366367
368369370371372373374375
376377378379380381382383
384385386387388389390391
392393394395396397398399
400401402403404405406407
408409410411412413414415
416417418419420421422423
424425426427428429430431
432433434435436437438439
440441442443444445446447
448449450451452453454455
456457458459460461462463
464465466467468469470471
472473474475476477478479
480481482483484485486487
488489490491492493494495
496497498499500501502503
504505506507508509510511
512513514515516517518519
520521522523524525526527
528529530531532533534535
536537538539540541542543
544545546547548549550551
552553554555556557558559
560561562563564565566567
568569570571572573574575
576577578579580581582583
584585586587588589590591
592593594595596597598599
600601602603604605606607
608609610611612613614615
616617618619620621622623
624625626627628629630631
632633634635636637638639
640641642643644645646647
648649650651652653654655
656657658659660661662663
664665666667668669670671
672673674675676677678679
680681682683684685686687
688689690691692693694695
696697698699700701702703
704705706707708709710711
712713714715716717718719
720721722723724725726727
728729730731732733734735
736737738739740741742743
744745746747748749750751
752753754755756757758759
760761762763764765766767
768769770771772773774775
776777778779780781782783
784785786787788789790791
792793794795796797798799
800801802803804805806807
808809810811812813814815
816817818819820821822823
824825826827828829830831
832833834835836837838839
840841842843844845846847
848849850851852853854855
856857858859860861862863
864865866867868869870871
872873874875876877878879
880881882883884885886887
888889890891892893894895
896897898899900901902903
904905906907908909910911
912913914915916917918919
920921922923924925926927
928929930931932933934935
936937938939940941942943
944945946947948949950951
952953954955956957958959
960961962963964965966967
968969970971972973974975
976977978979980981982983
984985986987988989990991
992993994995996997998999
Frame
0
Frame
1
Frame
2
Frame
3
Frame
4
Frame
5
Frame
6
Frame
7

To determine which frame a capcode is in, locate the last 3 digits of the 7 digit capcode in this table. The column will indicate the correct frame for all capcodes.

END OF SECTION
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