Receiver and receiver specifications
The index gap between the receiver and the receiver has sensitivity; the image rejection ratio (the gap between the radio and the receiver is large); the rectangular coefficient of the intermediate frequency filter (that is, the bandwidth ratio of 6db / 60db, a good receiver can reach less than 1.5, which The gap between the point radio and the receiver is also very large); dynamic range; frequency stability; and tuning step (high-end receiver can reach 1Hz).
The sensitivity of AM is almost the same. The radio frequency stability does not need to be too high. Receiving a strong signal in 5KHz steps does not require a high degree of stability.
The product orientation is different. If the radio station frequency needs to be accurate to 1Hz, there is no reason why the radio cannot do it. In other words, the radio is used for AM broadcasting. SSB and SFM are only incidental. It is difficult to require equal comparison for different product positioning (Measured under the same environment and frequency).
Sensitivity is a more practical equivalent comparison index, and to measure the sensitivity of AM, the sensitivity of long-wave, medium-wave and short-wave AM in the receiver is a few surprisingly high, it must be set aside SSB.
Both the radio and the receiver are receivers, but the product orientation is different, and it is difficult to compare. To compare, the performance of AM should be compared below 30MHz.
For the image rejection ratio, some high-IF secondary conversion radios can also be made higher. However, for a frequency conversion radio with an intermediate frequency of 465KHz, this indicator is meaningless. You can take a radio and put its frequency in the short wave to the mirror frequency and the frequency of the real radio station. Compare the volume, it should be almost the same! Mirror frequency suppression is also very important for the radio.
The rectangular coefficient of the intermediate frequency filter. This index cannot be too small for the radio, because if it is too small, the roll-off at the edge of the passband is extremely large, which will inevitably cause phase distortion and unsound sound quality. More importantly, the rectangular coefficient is small The cost of the filter is extremely high.
The communication receiver requires the highest possible adjacent frequency suppression, so it has to have a requirement for the rectangular coefficient of the intermediate frequency filter.It does not require any sound quality, only intelligibility and removal of adjacent frequency interference.
Dynamic range, this indicator is also more important. High-end receivers can add high-amplifier switches and attenuators divided into several gears, the purpose is to improve sensitivity without affecting its dynamic range. Radios rarely do this. High-end The starting point, time constant, and whether or not AGC is added to the communication receiver's AGC are adjustable, while general radios have AGC.
The frequency stability and stepping of the walkie-talkie, AM does not have too high requirements, but a senior HAM once took a manually tuned radio from outdoor to indoor in winter, and the radio ran, which is absolutely not acceptable. To remind buddy, the cost of stepping to 1Hz is very large, and now the stepping of many 10,000-level receivers is only 10Hz. For stability, many receivers use a constant temperature bath crystal oscillator, which is stable To one-billionth of a degree, such an oscillator will cost hundreds of dollars. Of course, it does not make sense for AM.
Both the radio and the receiver are receivers, but as a communication receiver, it is very different from the radio.
If you just want to listen to the radio, there is really no need to buy these expensive communication receivers. A 7600G is enough !!! But now the boundaries between radios and communication receivers are not so clear, and high-end radios have also added some only for receiving. Things that are unique to the machine, such as BFO, are not impossible for high-end radios to beat low-end receivers.
In a word, radish cabbage has its own love, touching the money in your pocket, thinking about what you want to do, let's go down! But pay attention, spend the same money, rather than buy second-hand communication receivers instead of SONY High-end radio !! This is my advice intercom !!!
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