An EPROM for the Lark has been developed that allows the machine to operate stand-alone without Ethernet support. This EPROM is intended for use during telephone registration testing of the Lark. A simple user interface is provided which allows the operator to place the Lark into several configurations suitable for testing. This document is filed as LarkRegistrationEPROM.tioga.

When power is first turned on, or whenever the telephone set is hung up, the Lark is established in an initial configuration.

The outside line is hung up.

The telephone set is set up so that DTMF signalling is directed to the DTMF decoder and so that voice from the outside line is sent to the telephone set receiver. Sidetone is enabled.

The output of the CODEC D/A converter is directed to the outside line, to the speaker, and to Line Out B.

Voice from the outside line is directed to Line Out A as well as to the telephone set receiver.

Power on -- sets up initial configuration.

Power off -- "revert" relays drop out and permit use of telephone set as a standard telephone.

Hang up telephone -- always returns Lark to inital configuration.

Lift telephone handset -- no action, but the DTMF keypad is not activated unless the phone is off hook.

DTMF 1 -- pick up the outside line.

DTMF 2 -- hang up the outside line.

DTMF 3 -- record the following digit sequence as a stored number of up to 18 digits. The number is terminated either by a '# or by hanging up the phone. A number stored in this way is remembered until another number is recorded or until power is turned off.

DTMF 4 -- dial the recorded number using the CODEC. The tones are generated at a level of about -3.5 dBm per tone at the outside line.

DTMF 5 -- turn on echo mode. More about this later.

DTMF 6 -- Connect the microphone to the CODEC input for transmission to the phone line.

DTMF 7 -- Connect Line In A to the CODEC input for transmission to the phone line.

DTMF 8 -- Connect Line In B to the CODEC input for transmission to the phone line.

DTMF 9 -- "Revert" the telephone set so that it is directly connected to the outside line as a standard telephone. Since in this configuration the telephone set is no longer connected to the DTMF decoder, the only way to return to the inital configuration is to hang up the telephone.

DTMF * -- Set up the speaker to listen to the outside line instead of the output of the CODEC.

DTMF 0 -- Connect the telephone set to the CODEC input for transmission to the phone line.

DTMF # -- If a number is being recorded, this will serve to end it. If a number is not being recorded, # has the same effect as hanging up and returns the Lark to the inital configuration.

This section expands upon the explanation of the action of the DTMF 5 command. Commands 6, 7, 8, and 0 connect various devices to the CODEC input "for transmission to the phone line." The way this works is that the source is filtered, digitized, passed through the level limiting system, converted back to analog, filtered again, and transmitted to the outside line if it is off hook. Alternatively, Echo Mode can be used. In echo mode, the steps are exactly the same except that the digital voice is not passed directly from A/D to D/A, but rather buffered in memory for a while. The effect of this slight delay, 40 milliseconds, is to give the voice a slight "echo" character.

There are two paths to the outside line. One path, active when the power is off or when the "Revert" mode has been entered via command DTMF 9, connects the telphone set directly to tip and ring of the outside line. In all other cases, voice directed to the outside line is produced by the D/A converter of CODEC 1. This converter drives a low pass filter to ensure that no out-of-band components reach the phone system. In addition, there is a limiting system which operates on the digital voice and serves to prevent levels higher than -9.5 dBm from reaching the phone system. Whenever the level, averaged over about 1.2 seconds, reaches about -9.5 dBm, 2.5 dB of loss is inserted, reducing the level to about -12 dBm. This limiting system is active at all times except during DTMF signalling of the recorded number. These DTMF tones are transmitted at about -3.5 dBm per frequency.

body node, repeat as needed