V.32bis/V.32 Modem Software
V.32bis/V.32 Software (Softmodems V32bis/V32)
The transmit and receive functions are called within a single function called V32_isr. This function is called to process received samples and to generate samples to transmit. The V32_init function is called to initialize the V.32/32bis modem. This function initializes the structure which contains all the memory required for the modem. The V.32/32bis modem can be adapted for a variety of sampling rates such as 9600 Hz or 7200Hz. The V.32bis/V.32 modem is designed to process data in 10ms intervals.
Features of V.32/V.32bis Software (Softmodems V.32/V.32bis)
- Full duplex mode of operation on switched and 2 wire, point-to-point, leased circuits.
- Channel separation is accomplished using echo cancellation techniques.
- QAM is used for each channel, with synchronous line transmission at 2400 baud.
- Data signaling rates: 14400, 12000, 9600, 7200, and 4800 bps synchronous.
- Trellis coding at rates from 7200 to 14000bps for V.32bis.
- For V.32, two alternative modulation techniques are used for a signaling rate of 9600bps, one uses 16 carrier states and one uses trellis coding with 32 carrier states.
- Exchange of rate sequences is provided during start-up to establish the data rate, coding, and any other special facilities.
- The frequency carrier operates at 1800Hz.
- Transmitted power levels conform to V.2
- The modulation rate is 2400 symbols.
- Reduced start-up time on recognized connections
- Support of modem-on-hold procedures in response to call-waiting events or outgoing call requests
- V.92 has the ability to temporarily put the 'Modem On Hold' (MOH) allowing users to receive a phone call without having to disconnect from their Internet session.
For official ITU-T standard on V.32bis/V.32, click ITU-T, V.32bis Standard, ITU-T, V.32 Standard.
For examples of GAO’s Modem Software Architecture, click GAO’s Modem Software Architecture.
For a complete list of GAO’s Modem Software products, please see GAO’s Softmodem List.