The RTL SDR is not the only such example though, for there is an entire class of cable modem chipsets that contain the essential SDR building blocks. The Hermes-Lite is an HF amateur radio transceiver project that uses an AD9866 cable modem chip as the signal end for its 12-bit SDR transceiver hardware with an FPGA between it and an Ethernet interface. It covers frequencies from 0 to 38.4 MHz, has 384 kHz of bandwidth, and can muster up 5W of output power.
I wish.Every time I looked in to it datasheets and even baseband interface standards like digirf 2.0 ware non-existent.And all the baseband stuff or most cable modem chips have no public documentation :(
A Radio Transceiver From A Cable Modem Chipset
Subscribers can access their cable modem service by simply turning on their computers, without dialing-up an ISP. You can still watch cable TV while using it. Transmission speeds vary depending on the type of cable modem, cable network, and traffic load. Speeds are comparable to DSL.
BPL is the delivery of broadband over the existing low- and medium-voltage electric power distribution network. BPL speeds are comparable to DSL and cable modem speeds. BPL can be provided to homes using existing electrical connections and outlets. BPL is an emerging technology that is available in very limited areas. It has significant potential because power lines are installed virtually everywhere, alleviating the need to build new broadband facilities for every customer.
CARLSBAD, Calif.--(BUSINESS WIRE)--MaxLinear, Inc. (NYSE: MXL), a leading provider of radio frequency (RF), analog and mixed-signal integrated circuits for the connected home, wired and wireless infrastructure, and industrial and multimarket applications, today announced that Aviat Networks (NASDAQ: AVNW) has selected the MxL1105 CMOS transceiver along with the MxL85652 and MxL85110 modems for its new line of WTM 4800 Multi-Band radios.
The MxL1105 is a single-chip broadband microwave transceiver that supports all licensed and unlicensed bands from 5GHz to 44GHz, including channel spacing options from 5MHz to 112MHz. With built-in Full Spectrum Capture (FSC) technology, the device supports channel aggregation mode which enables a second channel of any channel spacing to be processed within the same IC. The MxL1105 incorporates a full receive, transmit, feedback path, and all synthesizer components on a single chip, and can support code rates up to 4096 QAM. The closed-loop digital pre-distortion provides power amplifier (PA) linearization for a wide variety of PAs.
For all other microwave radio bands, designers can select chipsets to realize all of the licensed microwave radio bands from 6 to 42 GHz. Hittite has a large selection of components available for microwave radio applications. The IF transmitter and receiver chips HMC7436LP5ME and HMC7362LP6JE support all of the standard microwave frequency bands from 6 to 42 GHz.
Hittite Microwave continues to provide innovative, high performance, Antenna-to-Bits microwave radio solutions covering all bands from 6 to 42 GHz, while supporting both split-mount and full ODU style microwave radios. The IF transmitter and IF receiver chips HMC7436LP5ME and HMC7362LP6JE provide a very high level of integration, support all of the standard microwave frequency bands from 6 to 42 GHz, and form the core of these compact, high performance microwave radio chipsets.Hittite Microwave and Xilinx have successfully demonstrated a complete modem with 1024-QAM modulation in a 30 MHz channel over an 18 GHz microwave link. The BER of the complete modem was better than 10-9 over a wide range of attenuation settings. The IF transmitter and IF receiver chips are also capable of supporting modulations of 2048 and 4096-QAM.Hittite Microwave Corp.,Chelmsford, MA,txrx@hittite.com,www.hittite.com
A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carrier wave signals to encode digital information, while the receiver demodulates the signal to recreate the original digital information. The goal is to produce a signal that can be transmitted easily and decoded reliably. Modems can be used with almost any means of transmitting analog signals, from light-emitting diodes to radio.
Early modems were devices that used audible sounds suitable for transmission over traditional telephone systems and leased lines. These generally operated at 110 or 300 bits per second (bit/s), and the connection between devices was normally manual, using an attached telephone handset. By the 1970s, higher speeds of 1,200 and 2,400 bit/s for asynchronous dial connections, 4,800 bit/s for synchronous leased line connections and 35 kbit/s for synchronous conditioned leased lines were available. By the 1980s, less expensive 1,200 and 2,400 bit/s dialup modems were being released, and modems working on radio and other systems were available. As device sophistication grew rapidly in the late 1990s, telephone-based modems quickly exhausted the available bandwidth, reaching 56 kbit/s.
The rise of public use of the internet during the late 1990s led to demands for much higher performance, leading to the move away from audio-based systems to entirely new encodings on cable television lines and short-range signals in subcarriers on telephone lines. The move to cellular telephones, especially in the late 1990s and the emergence of smartphones in the 2000s led to the development of ever-faster radio-based systems. Today, modems are ubiquitous and largely invisible, included in almost every mobile computing device in one form or another, and generally capable of speeds on the order of tens or hundreds of megabytes per second.
Later developments would produce modems that operated over cable television lines, power lines, and various radio technologies, as well as modems that achieved much higher speeds over telephone lines.
A significant advance in modems was the Hayes Smartmodem, introduced in 1981. The Smartmodem was an otherwise standard 103A 300 bit/s direct-connect modem, but it introduced a command language which allowed the computer to make control requests, such as commands to dial or answer calls, over the same RS-232 interface used for the data connection.[14] The command set used by this device became a de facto standard, the Hayes command set, which was integrated into devices from many other manufacturers.
The introduction of microcomputer systems with internal expansion slots made small internal modems practical. This led to a series of popular modems for the S-100 bus and Apple II computers that could directly dial out, answer incoming calls, and hang up entirely from software, the basic requirements of a bulletin board system (BBS). The seminal CBBS for instance was created on an S-100 machine with a Hayes internal modem, and a number of similar systems followed.
The ITU standard V.34 represents the culmination of these joint efforts. It employed the most powerful coding techniques available at the time, including channel encoding and shape encoding. From the mere four bits per symbol (9.6 kbit/s), the new standards used the functional equivalent of 6 to 10 bits per symbol, plus increasing baud rates from 2,400 to 3,429, to create 14.4, 28.8, and 33.6 kbit/s modems. This rate is near the theoretical Shannon limit of a phone line.[20]
At that time, USRobotics held a 40% share of the retail modem market, while Rockwell International held an 80% share of the modem chipset market. Concerned with being shut out, Rockwell began work on a rival 56k technology. They joined with Lucent and Motorola to develop what they called "K56Flex" or just "Flex".
While Carterfone required AT&T to permit connection of devices, AT&T successfully argued that they should be allowed to require the use of a special device to protect their network, placed in between the third-party modem and the line, called a Data Access Arrangement or DAA. The use of DAAs was mandatory from 1969 to 1975 when the new FCC Part 68 rules allowed the use of devices without a Bell-provided DAA, subject to equivalent circuitry being included in the third-party device.[33]
The audio sent and received on the line by a modem of this type is generated and processed entirely in software, often in a device driver. There is little functional difference from the user's perspective, but this design reduces the cost of a modem by moving most of the processing power into inexpensive software instead of expensive hardware DSPs or discrete components.
Fax modems can be used for computer-based faxing, in which faxes are sent and received without inbound or outbound faxes ever needing to ever be printed on paper. This differs from efax, in which faxing occurs over the internet, in some cases involving no phone lines whatsoever.
The ITU-T V.150.1 Recommendation defines procedures for the inter-operation of PSTN to IP gateways.[42] In a classic example of this setup, each dial-up modem would connect to a modem relay gateway. The gateways are then connected to an IP network (such as the Internet). The analog connection from the modem is terminated at the gateway and the signal is demodulated. The demodulated control signals are transported over the IP network in an RTP packet type defined as State Signaling Events (SSEs). The data from the demodulated signal is sent over the IP network via a transport protocol (also defined as an RTP payload) called Simple Packet Relay Transport (SPRT). Both the SSE and SPRT packet formats are defined in the V.150.1 Recommendation (Annex C and Annex B respectively). The gateway at the remote end that receives the packets uses the information to re-modulate the signal for the modem connected at that end.
Dial-up modem use in the US had dropped to 60% by 2003, and stood at 36% in 2006.[citation needed] Voiceband modems were once the most popular means of Internet access in the US, but with the advent of new ways of accessing the Internet, the traditional 56K modem was losing popularity. The dial-up modem is still widely used by customers in rural areas where DSL, cable, wireless broadband, satellite, or fiber optic service are either not available or they are unwilling to pay what the available broadband companies charge.[46] In its 2012 annual report, AOL showed it still collected around $700 million in fees from about three million dial-up users. 2ff7e9595c
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