Hi,

The standard used by TDDs is the Baudot code implemented
asynchronously at 45.5 (USA), 1 start bit, 5 data bits,
and 1.5 stop bits.

In your example I see only the 5 data bits.

From the PBP manual:

FREQOUT generates tones using a form of pulse width modulation.
The raw data coming out of the pin looks pretty scary. Some kind
of filter is usually necessary to smooth the signal to a sine
wave get rid of some of the harmonics that are generated.

* * *

Two questions when you use the FREQOUT command + filter:

1. What happen during transitions with the output signal?
2. Is the the output phase-continuous during transitions?

The output of the sinusoidal FSK Generator has to be
phase-continuous during transitions.(Mark and space transitions).

See page 2 of this PDF for Frequency shift keying (FSK) signal.
http://www.cs.sfu.ca/CourseCentral/3...s/lecture7.pdf

* * *

What about using the HW tone generator XR 2206 from Exar Corporation?
(The input for the tone generator XR 2206 is serial data).

XR-2206 monolithic function generator
Datasheet Rev 1.03
http://www.exar.com/products/XR2206v103.pdf

Page 9

FSK Generation
Figure 13 shows the circuit connection for sinusoidal FSK
signal operation. Mark and space frequencies can be
independently adjusted by the choice of timing resistors,
R1 and R2; the output is phase-continuous during
transitions. The keying signal is applied to Pin 9.


Again, start with the decoder part of your project.
The encoder part is easy.

Best regards,

Luciano