There are many advantages to a telephone based control path. This allows users to gain access to the system if they do not have a radio available, or if they are in a location that won't allow them access to the system via an RF input. It is also useful if the user is to do a significant amount of system configuration because entry of commands via the telephone can be done while the repeater is in use without disrupting its operation. There is also a degree of privacy that is conveyed by using the telephone as a control path. With the advent of easily obtained DTMF decoders it is becoming less difficult for unscrupulous persons to decode control codes -- especially if there is a control or system operator parked on the repeater for several minutes performing configuration functions.
The prime disadvantage to the control autopatch lies in the fact that the DTMF decoder can only service one source at a time. Thus, when a control autopatch is in progress, DTMF entries from any port on the FF-800 will not be muted or recognized. This is usually not a significant problem since most users monitor repeater activity to detect urgent or emergency traffic that might need access to the autopatch, or other repeater services.
The system operator can enable or disable the control autopatch as well as determine the number of rings that are required before the FF-800 will answer. Other support routines allow the operator to monitor repeater traffic from the phone, initiate a reverse control autopatch, or logoff from the telephone control path. The following paragraphs detail these commands and illustrate them with examples.
Command Delimiter Access: N/A
(#*) normal delimiter
(#) or (D) optional delimiters (if selected)
The Command Delimiter is not a command, but must be used during all control patch command entries. Due to the lack of a convenient source of COS for phone traffic, the Command Delimiter is a unique, DTMF sequence that allows the operator to tell the FF-800 that the command entry is complete. The controller will not respond to DTMF digits entered from the control patch until it detects this two digit sequence. The normal delimiter (#*) may be used from any DTMF input; the optional delimiters are somewhat different: the (#) digit is only used from the control autopatch while the (D) digit is used on all other DTMF inputs.
Control Patch Enable Access:
(cnfg) (530) ; (on/off)
Response: "R A P" + "On" or "Off"
If the control autopatch is disabled, the FF-800 will not answer the telephone line and will therefore not accept control commands via the phone.
Number of Rings Access:
(cnfg) (532) ; (#rings)
Response: "R I N G" + #rings
This command allows the user to set the number of rings required by the FF-800 before it will answer a potential control autopatch. NOTE: if #rings = 0, the FF-800 will not answer for 256 rings (which effectively de-activates the control autopatch).
Don't Answer Next Access: CONTROL
Response: "Control Telephone Call Cancel"
This command causes the FF-800 to ignore the next ring cycle from the phone line. If no ring condition is detected within 5 minutes after this command, the FF-800 will resume normal ring detect status.
Control Patch Logon Access: GENERAL
Response: "O K"
When the FF-800 answers the telephone for a potential control autopatch, it responds "C A P Up" (or user defined message) and then sets an entry timer of 13 seconds which allows the operator time to enter the logon command. If the command is not successfully entered during this period, the controller will hang-up and abort the logon process until it answers the phone again. When this command is entered, it responds with "O K" to indicate to the operator that the logon was successful. The logon duration is 15 minutes and is automatically reset to 15 minutes after every valid DTMF command.
Control Patch Logoff Access: CONTROL
Response: "O K"
The operator must be sure to use this command to logoff from the FF-800 system prior to hanging up from the control autopatch session. Failure to properly logoff may result in loss of repeater control for up to the amount of time programmed into timer#13. The control receiver input or the Auxiliary DTMF input are the only command channels that are active during a control patch. Thus, if a control patch is not properly disconnected, these two paths are the only way to remotely regain the normal control paths. Of course, the normal operation of the controller is not disrupted, the FF-800 simply won't respond to any DTMF inputs from main or link ports. NOTE: The Autopatch Disconnect command can also be used to logoff from the control patch.
Control Patch Monitor Access:
(cntl) (406) (on/off)
Response: "M O N" + "On" or "Off"
While in the control patch session, the operator may find it useful to monitor repeater traffic. The patch monitor command allows the user to monitor the traffic on the repeater without passing phone line audio to the repeater output, and without indicating the presence of the operator on the control patch. NOTE: The Autopatch Disconnect command can also be used to turn off the control patch monitor funtion. When using the Autopatch Disconnect command in this fasion, the control patch will not be disconnected (unless Autopatch Disconnect is issued twice).
Sysop Reverse Patch Access: GENERAL
Response: "Control Telephone Call" or user defined message
Another feature unique to the control patch is that of the Sysop Reverse Patch. This command connects the operator on the control patch to the repeater output. This command places the FF-800 in the autopatch mode, and the operation of the repeater is just as though an autopatch was made except that the control path remains to the phone line (ie., the control patch operator is still in control). The normal autopatch, and activity timers are both in effect during the Sysop Reverse Patch, so if no activity is present on the repeater, the activity timer will eventually deactivate the Sysop Reverse Patch. The normal Autopatch Disconnect command is used by the control patch operator to deactivate the Sysop Reverse Patch. It should be noted that no matter how the Sysop Reverse Patch feature is disconnected, the operator will always be returned to the control patch mode. Thus, the operator can not directly logoff from the Sysop Reverse Patch mode, first, the reverse patch must be deactivated, then the logoff command can be entered.