RTTY decoder version 2.02, original project at http://www.kk5jy.net/modem-v2/ designed by Matt Roberts KK5JY added LCD function and menus by PD0LEW included non word breaking. Adjustable baud rate and AFSK tone frequencies 2210, 1500, 1360 and 1000 Hz., polarity, squelch, time out squelch, line input volume. With advanced tuning indicator < = >.
Embedded Files
The decoder tested with MixW http://mixw.net/
Character Oled 128 x 64 display mounted in enclosure with double sited tape 1.8 mm thick.
Small housing 110 x 71 x 25 mm
The decoder under test (first issue)
The PCB fits after a small modification exactly in the enclosure.
The cabinet in two parts
Teensy 3.6 and audio board directly soldered on the PCB, use 90 degrees header for the display connection
For my RTTY and CW decoders I use Hamradio software called MixW this program is easy to use and performs very well.
Polarity reversed
Polarity not reversed
Device parameter depends on audio board
The unit is ready for RTTY reception.....
Version number, name and call can be changed
Current production serial command sets are described below:
Current production serial command sets are described below:
Both modems support a number of commands, each of which has the same meaning regardless of the operating mode. Some of these can be used by a user interface application to identify which modem is connected, and what commands are supported:
DOC
This returns the "doc string" which lists the commands that are supported by the modem. In future revisions, the DOC string will support detailed query of individual commands, to better support fully-generic user interfaces.
VERSION
Query the version string of the firmware.
MODE
Query the operating mode of the modem. This will return either CW or RTTY.
ECHO
Set or query terminal echo. ECHO=0 will disable echo of all data sent to the modem. ECHO=1 will enable echo of all bytes sent to the modem, whether commands or data. ECHO=2 will enable echo for transmit data only, and is intended for use when the modem is being driven by a dedicated application, rather than a simple terminal. Echoing the data but not the commands simplifies the task of separating the data and command streams.
EC
Erases the EEPROM when set to a value of 1. This is handy when reusing a board that already has EEPROM data stored in it.
DEV
Returns a smoothed and scaled value indicating the received signal offset from the center frequency of the modem. The value returned is unitless, and possibly subject to scale and offset values configured with other commands.
PTTIN
Get or set the number of milliseconds between asserting PTT and starting to send transmit data.
PTTOUT
Get or set the number of milliseconds between the trailing edge of the last transmitted data element, and when PTT is released.
LEVEL
Returns the normalized audio level, in the range of 0 to 100. This value is latched and resets each time this is called. The value returned is the largest value encountered since the last LEVEL call, making this a 'peak' level query.
LINEIN
Get or set the volume level of the LINE IN channel of the codec's mixer. Valid values are zero to 15, and each value corresponds to a specific peak-to-peak input voltage that will produce full scale readings from the A/D converter, these voltage levels are documented within the INO file. Larger values produce more gain. This setting should be adjusted to match the radio output to produce the largest LEVEL value that does not clip on strong signals.
DS
Returns the current state of the detector; the value is mode-dependent, and is mainly for debugging.
Text from Matt Roberts http://www.kk5jy.net/modem-v2/
The CW modem also has a number of commands specific to CW operation.
The CW modem also has a number of commands specific to CW operation.
RXWPM
Get or set the speed at which the decoder will expect to receive CW data. If RXMODE is set to AUTO, this value can change between queries.
TXWPM
Get or set the speed at which the encoder will produce CW elements for transmission.
RXMODE
Enable or disable decoder speed auto-tracking. Valid values are MANUAL or AUTO.
TXMODE
Enable or disable whether the encoder speed auto-tracks the receiver. Valid values are MANUAL or AUTO.
CRLFBT
Enable or disable whether to convert BT prosign to CR/LF, or vice versa. 0 = disabled, 1 = enabled. If enabled, this will cause the ENTER key on the keyboard to generate a BT prosign. It will also cause a received BT prosign to generate a CR/LF on the terminal.
DOT
Returns the decoder's current dot length, in milliseconds.
BOUNCE
Gets or sets the sampling interval of the software debounce filter for the CW input when an external hardware tone detector is used.
When using the LM567 emulation option (see above), there are a set of additional commands that can either adjust or query the operation of the decoder:
PLLOFF
Get or set the PLL reporting offset. This is used to adjust the reported PLL offset so that a #DEV=0; is returned on a perfectly-centered tone.
PLLGAIN
Get or set the PLL reporting gain. This is used to adjust the magnitude of the #DEV; for a given shift in frequency. A larger value will cause #DEV; to return larger offset values.
PLLLOW
Get or set the PLL low-side asymmetry correction. This applies a scale to the #DEV; reading when that reading is less than zero. This corrects for assymetry in the PLL output either side of zero.
PLLI
Get or set the PLL in-phase integration window length.
PLLQ
Get or set the PLL in-quadrature integration window length.
PLLR
Get or set the PLL rail magnitude.
I
Returns the current in-phase average from the PLL.
Q
Returns the current in-quadrature average from the PLL.
Text from Matt Roberts http://www.kk5jy.net/modem-v2/
The RTTY modem also has a number of commands specific to RTTY operation.
The RTTY modem also has a number of commands specific to RTTY operation.
HALFBIT
Set between 10 and 48
CSET
Get or set the character set to use; valid values include BAUDOT, ASCII7, and ASCII8.
UOS
Enable or disable unshift-on-space.
REV
Reverse the meaning of the two tones, for RX, TX, BOTH, or NONE. This will reverse mark and space polarity in the decoder, and in the generated keying waveform.
TUNE
Key the transmitter with a constant carrier for tuning purposes. 1 to enable, and 0 to disable.
SQL
Squelch threshold, measured as a deviation level; set to zero to disable.
SQTO
Squelch timeout, in milliseconds.
HASH
Transmit a hash (#) character. If a hash (#) character is received in the audio stream from the receiver, a #HASH; response will be sent to the host port unsolicited. This allows the hash character to be passed in each direction without disturbing the command processing state.
Text from Matt Roberts http://www.kk5jy.net/modem-v2/
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