It's the additional information to plug-ins DCD and sndRemote

Bi-phase coding
A rising edge within a time window is equivalent to a "1", a falling edge represents a "0":

Pulse-distance modulation

Pulse-length code

In most remote-control transmission systems, only small data rates are transmitted to control the functions of home entertainment equipment. A vital pre-requisite is the safety of transmission where an incorrect interpretation of the transmitted code is not permissible. Unintelligible signals must be ignored. Usually, commands are repeated until the remote-con-trolled device reacts as desired. The operator can directly observe the result of pressing a key by visual feedback.
The commands can be transmitted by variation of the coding of the optical carrier. Some methods of modulation have been established. Nowadays, only the digital transmission of words is used where the word length can vary which means one word can include a different number of bits.
The three commonly used representations of a bit in remote-control systems are described in the following paragraphs.
Special types for different operating frequencies are available in the range from 30 kHz to 60 kHz. Standard types are available for the frequencies 30 kHz, 33 kHz, 36 kHz, 36,7 kHz, 38 kHz, 40 kHz and 56 kHz. Other frequencies in this range can be realized on request.
The data words to be transmitted consist of a defined number of bits. Word lengths and coding method are defined in the transmission standards. Several transmission standards are now accepted worldwide. Some of them are described in the following paragraphs.
In European equipment, the most commonly used standards are the RC 5 code and the RECS 80 code. Another popular transmission language is the NEC code (Far East).
In addition, many important consumer electronic product manufacturers have their own company standard regarding the transmission code.

Standards of codings

In the RC 5 standard, a bi-phase coding is applied. The carrier frequency is fixed at 36 kHz. Similar transmission standards are used in the frequency range between 30 kHz and 56 kHz.
The transmission of a word begins with two start bits, followed by a toggle bit. The toggle bit changes its value at each key operation. With this change, an interruption of the transmission link can be distinguished from a multiple key pressing. The five address bits address the device to be controlled. The command bits contain the information to be transmitted.
Each bit in a data word consists of a burst of 32 pulses with a repetition rate of 36 kHz. The equivalent times are shown in the pulse diagrams.


The NEC code starts the transmission using a so-called leader code, a burst of a length of 9 ms, followed by the data word after a pause of 4.5 ms. This leader code is responsible for leveling the internal control loops in the receiver modules.

As long as a key is pressed, only the leader code is repeatedly transmitted, followed by a single bit. A specialty of this code is the property of constant word length in connection with a pulse-distance modulation. Both address and command bit are transmitted twice, first as the normal byte followed by the inverted byte. This is shown in figure 9. The burst defining a bit contains 22 pulses each of a length of 8.77 µs with a period of 26.3 µs. A "0" is represented by a pulse distance of 1.125 ms, the "1" with 2.25 ms, respectively. 8 address bits are used to identify the device to be con-trolled. A further 8 bits are used for the transmission of the command. As mentioned above, the words are always followed, without a pause, by the inverted words, e.g., the transmission of the address "00110111" and the command "00011010" is performed by sending the word: "00110111'11001000'00011010'11100101".

Used by HITACHI, NOKIA, AIWA, AKAI, AverMedia.

Creative RM-900 (SoundBlaster Live Platinum) sends data word twice. The first address byte is not equal inverse of the second address byte (C1h and 44h). For compatibility the first 2 address bytes are not compared and used both.
RECS 80 / RC-4
With a length of 70 ms, the data word in the RECS 80 code is nearly three times as long as that in the RC 5 code. The RECS 80 code operates with a digital pulse-distance modulation. As in the RC 5 code, toggle, address and command bits are used. Sometimes, a flash mode is found in combination with the RECS 80 code where single pulses of infrared radiation are transmitted instead of bursts. A carrier frequency of 400 kHz is also used instead of the common carrier in the range between 30 and 56 kHz.

Used by JVC.

SONY / Panasonic

Pulse-length modulation. Up to 20 data bits.

Result of decoding in a plug-ins DCD and sndRemote is a 28-bit identifier such as 0FAAAACC. Where F - a flag determining modulation, A - the address, C - command. For SONY the last 24 bits determine a code of command.

AverMedia TVPhone98 w/VCR






Pioneer CU-PD046 (CD Player Pioneer PD-203)

TV Tuner Tekram M205