wireless cell cellular modem for data access solutions
(looks and feels like a standard RS 232 AT command compatible modem)
VDC power / - 40 to + 85 C. temp rating option

AMPS Advanced Mobile Phone Service

The first cellular networks where analog systems. The Advanced Mobile Phone Service (AMPS) is in wide use even today, almost 25 years after it was introduced. AMPS was conceived by Bell Labs in the 1970s,. The AMPS air interface is specified in EIA/TIA-553. AMPS is based on FDMA.

The FCC allocated a total of 50 MHz (25 MHz on the A side and B side) in the 800-MHz spectrum for AMPS. Each voice channel is allocated a 30-KHz portion of the bandwidth within the AMPS frequency allocations. Which limits the number of channels for voice traffic to 312 calls at one time? AMPS uses the seven-cell frequency reuse method. Control channels are used to set up and clear calls as well as other control messages. Each band (25 MHz) contains 21 control channels. When a mobile station is not in session, it must monitor designated control channels. It tunes and locks into the strongest channel to receive system information. The forward control channel (FOCC) is a data stream from the base station to the mobile, and the reverse control channel (RECC) is from the mobile to the base station. Voice conversation is carried over the forward voice channel (FVC) and the reverse voice channel (RVC)_..

The ESN (Electronic Serial Number) for a mobile is a 32-bit number that uniquely identifies a mo­bile and is set up by the mobile manufacturer.

The system IDs SID (System IDentification) is a 15-bit binary numbers that are assigned to cellular systems. One of the uses of the SID is to determine a home network from a roaming network.

The MIN (Mobile Identification Number) is a 34-bit number that is derived from the mobile terminal's 10-digit telephone number.

Data services in AMPS are straightforward and analogous to dial-up net-working. Because AMPS is an analog technology, it is possible to make use of standard modems directly with AMPS. Data rates are at a maximum of 14.4 Kbps irrespective of the modem protocol (v.90 or others).

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What is CDPD

CDPD (Cellular Digital Packet Data) is a specification for supporting wireless access to the Internet and other public packet-switched networks. Cellular telephone and modem providers that offer CDPD support make it possible for mobile users to get access to the Internet at up to 19.2 Kbps . Because CDPD is an open specification that adheres to the layered structure of the Open Systems Interconnection (OSI) model, it has the ability to be extended in the future. CDPD supports both the Internet's IP protocol and the ISO Connectionless Network Protocol (CLNP).

CDPD also supports IP multicast (one-to-many) service. With multicast, a company can periodically broadcast company updates to sales and service people on the road or a news subscription service can transmit its issues as they are published. It will also support the next level of IP, IPv6.

For the mobile user, CDPD's support for packet-switching means that a persistent link isn't needed. The same broadcast channel can be shared among a number of users at the same time. The user's modem recognizes the packets intended for its user. As data such as e-mail arrives, it is forwarded immediately to the user without a circuit connection having to be established. There is a circuit-switched version, called CS CDPD, that can be used where traffic is expected to be heavy enough to warrant a dedicated connection.

as you may well know the FCC has let the carriers discontinue the CDPD networks
which are now being replaced by the GPRS and 1xRTT digital networks that run on the IP networks

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