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Starting in 1958, EICO produced amateur radio equipment often in kit form, such as the EICO 720 and 730 transmitters. Later in the 1960s they made the EICO 753 SSB transceiver for amateur radio use. Unfortunately problems with the 753--or seven drifty three-- damaged their reputation which led to their decline.
In the following there are lists of sites of notable radio transmitters.During the early history of radio many countries had only a few high power radio stations, operated either by the government or large corporations, which broadcast to the population or to other countries.
Thus at 4 kHz, the noise level is 20 dB higher than at 400 Hz, and at 40 kHz it is 40 dB higher. So the L-R subcarrier, whether DSB or FM, is accompanied by a high level of noise. FM uses pre-emphasis to overcome high frequency noise. Sounds above 2 kHz are boosted 6 dB per octave at the transmitter by a pre-emphasis circuit.
IQ imbalance is a performance-limiting issue in the design of a class of radio receivers known as direct conversion receivers. [a] These translate the received radio frequency (RF, or pass-band) signal directly from the carrier frequency to baseband using a single mixing stage.
The transmitter and receiver can use fixed tables of frequency-hopping patterns, so that once synchronized they can maintain communication by following the table. In the US, FCC part 15 on unlicensed spread spectrum systems in the 902–928 MHz and 2.4 GHz bands permits more power than is allowed for non-spread-spectrum systems.
On the receiver side, frequency drift was mainly a problem in early tuners, particularly for analog dial tuning, and especially on FM, which exhibits a capture effect. However, the use of a phase-locked loop (PLL) essentially eliminates the drift issue. For transmitters, a numerically controlled oscillator (NCO) also does not have problems with ...
A personal FM transmitter is a low-power FM radio transmitter that broadcasts a signal from a portable audio device (such as an MP3 player or a smartphone) to a standard FM radio. Most of these transmitters plug into the device's headphone jack and then broadcast the signal over an FM broadcast band frequency, so that it can be picked up by any ...
Wide FM, 20.0 kHz width, ±5 kHz deviation, still widely used for amateur radio, NOAA weather radio, marine, and aviation users and land mobile users below 50 MHz [2] 11K2 F3E Narrow FM, 11.25 kHz bandwidth, ±2.5 kHz deviation – In the United States, all Part 90 Land Mobile Radio Service (LMRS) users operating above 50 MHz were required to ...