Wireless modem

• US 7,409,195 B2
• Filed: 11/26/2003
• Issued: 08/05/2008
• Est. Priority Date: 09/08/2000
• Status: Expired due to Fees

• Current Assignee: NEBO Wireless LLC
• Original Assignee: NEBO Wireless LLC
• Inventors: Lin, Ernie, Giger, Adolf J.
• Primary Examiner(s): Tran; Tuan A
• Application Number:
  US10/723,442
• Publication Number:
  US 20040171348A1
• Time in Patent Office: 1,714 Days
• Field of Search: 455 411- 412, 455/63.1, 455/74, 455/74.1, 455/78, 455/550.1, 455/552.1, 4555561-5562, 455557-558, 4551142-1143, 4551271-1272, 455/522, 375220-222, 379/386, 379/423, 37938803-38806, 37939003-39004, 379/395
• US Class Current: 455/127.2
• CPC Class Codes: H04M 1/738 Interface circuits for coupling substations to external telephone lines H04M1/78 takes precedence

Abstract

A modem includes a base unit for transmitting a data signal, and a communication card which receives the data signal from the base unit over a wireless medium and which performs echo canceling on the data signal. The base unit is in communication with a telephone line and receives an original signal from the telephone line. The base unit generates an RF modulated signal based on the original signal. The base unit includes a transmitter for transmitting the data signal. Circuitry in the base unit receives the original signal from the telephone line and generates a combined data signal from the original signal and echo signals and maintains a peak voltage of the combined signal which is within the linear amplification region of the transmitter.

Claims

1. An apparatus comprising:

a base unit for coupling to a telephone line; and

a remote unit for communicating with the base unit over a wireless medium;

wherein the base unit includes a transmitter for direct analog modulation of an original analog voiceband data signal received over the telephone line and transmitting the modulated signal over the wireless medium, and level control circuitry coupled to the transmitter that controls a level of the original analog voiceband data signal to be substantially in a linear range of the transmitter;

wherein the remote unit includes a receiver for receiving the modulated signal over the wireless medium and direct analog demodulation of the original analog voiceband signal, and an interface to a modem circuit for decoding a data stream encoded in the original analog voiceband signal;

wherein the level control circuitry that controls a level of the signal comprises an automatic gain control circuit that controls a peak level of the signal; and

wherein the automatic gain control circuit uses a dial tone of a telephone connection or a DC current of a telephone loop to set a gain level for the original signal at a beginning of communication, the gain level remaining substantially constant during communication.

2. The apparatus of claim 1, wherein the data signal is transmitted over a radio channel using multi-level frequency shift keying (FSK) modulation.

3. The apparatus of claim 1, wherein the remote unit is in communication with the base unit and a computer, the remote unit receiving an original voiceband data signal from the computer, generating an RF modulated signal based on the original signal from the computer, and transmitting the RF modulated signal to the base unit.

4. The apparatus of claim 3, wherein the remote unit includes an RF transmitter and an RF receiver, the remote unit establishing wireless communication with the base unit, the remote unit communicating with the base unit by wireless communication via the RF transmitter and the RF receiver and the remote unit communicating with the computer via a wired link.

5. The modem of claim 3, wherein the remote unit includes a switch for selecting a type of medium over which to transmit and receive the data signal.

6. The apparatus of claim 1, wherein

the base unit includes a ring detector coupled to the telephone line for detecting a ring signal on the telephone and providing a ring indication signal to the transmitter for transmission over the wireless medium to the remote unit;

and

the remote unit includes a ringer emulator coupled to the receiver for receiving the ring indication signal and emulating a ring signal on a telephone interface.

7. The apparatus of claim 1 wherein the remote unit further comprises a modem circuit coupled to the remote unit.

8. The apparatus of claim 7 wherein the modem circuit includes an echo canceller for reducing echoes on the demodulated original analog voiceband data signal and a CODEC for decoding the original analog voiceband data signal.