DE2263137B2 - Device for the implementation of very high frequencies - Google Patents

Description

Frequency converter in directional radio links and for supplying residential areas that are difficult to access in terms of HF with radio and television programs have been known for years.

While the implementation to supply residential areas, i. H. the implementation of received Television and radio frequencies in those of other neighboring areas of medium frequencies does not pose any particular problems, make frequency conversions of higher frequencies in radio links a considerable amount of technical resources is required. The ones for the supply of residential areas with radio and television ever denser occupancy in the previous Frequency ranges makes a switch to the SHF frequency band above the UHF range indispensable. However, a prerequisite for technically perfect use is mastery of the In the high frequency area, production techniques that are becoming more and more complex and complex the necessary facilities, such as frequency constancy, freedom from spurious emissions, etc., in particular also with converters.

The converters most commonly used in microwave links at the moment work with double conversion and a relatively large frequency difference between the input and output signal. The required frequency spacing is achieved by a so-called offset oscillator that works with the auxiliary frequency mixed for the output mixer generates the auxiliary frequency for the input mixer. Here must the required signal-to-noise ratio of the auxiliary frequency for the input mixer through particularly complex measures increase.

The invention specified in claim 1 has the object of providing a device of the initially to create the type described, with the help of which the implementation of extremely high frequencies in a simple Circuit technology, mastered with simple components and with little effort and interference-free can be.

By designing the device according to the invention, it is possible to use the z. B. In the SHF range, the effort required to achieve the required frequency stability should advantageously be relocated to lower frequency ranges that are technically easier to control, since the frequency constancy of the output signal in the SHF range is independent _{of the frequency constancy of the auxiliary frequency / t.} For the preparation of this auxiliary frequency z. B. no additional offset oscillators with the associated mixers and bandpass filters are required. In addition, the frequency difference between the input and the output signal can be selected as small as desired.

A particular advantage of the device according to the invention can be seen in the fact that a fixed auxiliary frequency /; ,, also for the conversion of other RF signals for the respective common oscillator can be chosen, so that there is the particular manufacturing advantage that a single training of such a common oscillator with constant auxiliary frequency ///, for these different ones Frequency converter can be provided.

The relatively low quality requirements for the individual assemblies, as they are in the facility are used according to the invention, are in no relation to the previously known Facilities in the areas of maximum frequencies with their extreme quality requirements. Seen in this way, the invention ensures considerable economic progress.

In order to achieve the fullest possible utilization of the bands in the SHF and UHF ranges when converting HF signals of different frequencies, a further embodiment of the invention is characterized in that an HF signal to be converted using the selected common auxiliary frequency J _11x on the predetermined lower band limit in the range of extremely high frequencies is converted to the beginning of the band of the range of medium frequencies.

In a further embodiment of the invention, in particular for television signals, there is an additional one economic advantage in that the implementation from a range of medium frequencies (3rd IF) over another IF, e.g. B. via the standard IF (2nd IF). The components required for this are technical problem-free and known for years.

An exemplary embodiment of the invention is described below with reference to the drawing. It means

F i g. 1 is a block diagram of the facility,

F i g. 2 shows a schematic representation of the individual frequency ranges and the conversion of the RF signal.

The SHF signal f _E arriving at the input reaches the input mixer 2 via a bandpass filter 1. With the aid of the auxiliary frequency } _{H x} generated in a relatively simple oscillator 3, the input mixer 2 is converted to a lower frequency range, in particular to the UHF -Area that follows input mixer 2 «. Bandpass filter 4 is designed so that the signal to be transmitted lies within its useful bandwidth (1st IF). A further auxiliary frequency f _Hi generated in the oscillator 6 is fed together with the signal to be transmitted arriving from the bandpass filter 4 to the downstream mixer 5, which converts it into the known TV standard (2nd IF). In the IF module 7, the signal to be transmitted is processed using conventional technical means before it is converted back up into the UHF frequency range with the aid of the mixer 8 with simultaneous supply of a third auxiliary frequency / ". Formed in the oscillator 9 ( 3rd IF).

The bandpass filter 10 following the mixer 8 is again designed so that only the signal to be transmitted can pass and both the auxiliary frequency / _w “and the undesired sideband are sufficiently suppressed.

The following output mixer 11 finally sets the signal to be transmitted with the help of the same auxiliary frequency / _Hl formed in the oscillator 3 and already used for the downward conversion into a channel spacing of the corresponding channel spacing already selected in the UHF range from the difference / _W o - fn _a SHF area. The subsequent bandpass filter 12 prevents the transmission of the auxiliary frequencies / _rt and the undesired sideband.

In order to obtain a better overview, in the block diagram of FIG. 1 the individual Steps necessary assemblies, such as amplifiers, etc., omitted.

For a better understanding, one recognizes in FIG. 2 the basis for the individual implementations Frequency hops.

Starting from f _E, the frequency bands are plotted schematically one after the other from left to right in the top row. In the lower row, these appear analogously from right to left.

The auxiliary frequencies are noted between the dimension lines and can be represented as follows:

ZF ₁ - Ie-Ih ₁ ; IF ₃ = IF ₂ + J _{n 3} ;

this results in:

Ia ⁼ fiii + / «3 ~
thus follows

ZF ₂ = ZF ₁ - f _H2 U = ZF ₃ + f _Hi

H-ti

ill

/ f

Ih t

From the calculation process shown, it is also clear that the common auxiliary frequency j _{tl is} canceled out in the course of the conversion process and consequently no longer has any influence on the frequency constancy of the transmitted RF signal. This results in a fourfold implementation that can be carried out in practice.

1 sheet of drawings

Claims (3)

Patent claims: 1. Device for frequency-stable conversion of a modulated RF signal of a defined bandwidth from the range of extremely high frequencies to an adjacent frequency in the same range extremely high frequencies with the help of repeated implementation in areas and out of areas medium frequencies, characterized in that for the implementation from the range of extremely high frequencies in such a medium frequency and the reconversion from the range of medium frequencies The auxiliary frequencies required in the area of extremely high frequencies are identical and a common one for both the input mixer (2) and the output mixer (11) Oscillator (3) can be removed, with the desired frequency spacing in the range extremely high frequencies inevitably due to the choice of the frequency spacing in the medium range Frequencies is determined. 2. Device according to claim 1, characterized in that with the help of the selected common auxiliary frequency f _{H t} an RF signal to be converted on the predetermined lower band limits / '.e in the range of extremely high frequencies is converted to the beginning of the range of medium frequencies. 3. Device according to claim 1 or 2, in particular for television signals, characterized in that that the conversion from one range of medium frequencies (I.ZF) to another Medium frequency range (3rd IF) over another IF, e.g. B. via the standard IF (2nd IF)