Circuit for testing the function of mobile receiving installations
First Claim
1. A circuit for testing the working function of a mobile receiving installation (20) having at least one receiving antenna (5) in a high frequency connection with a superheterodyne receiver (1), the superheterodyne receiver (1) having an image frequency filter (4), an oscillator (9), an IF-signal (11) and a measuring system (10) coupled to the IF-signal for detecting the level of the received signal, the circuit comprising:
- a circuit arrangement (2) disposed within the receiving installation (20) and coupled to the superheterodyne receiver (1) and the at least one antenna (5), said circuit arrangement comprising;
a frequency mixer (3) having a first input coupled to an output of oscillator (9) in superheterodyne receiver (1), a second input and an output, oscillator (9) generating an oscillator signal (8);
a feedback loop connecting the IF-signal (11) to said second input of said frequency mixer (3) to provide a self excitation condition, thereby generating an IF-carrier frequency (22), of limited amplitude from the IF-amplifier part of the superheterodyne receiver (1);
said frequency mixer (3) producing an HF-output signal (12) having a constant amplitude with respect to time at its output, said HF-output signal (12) having a frequency conforming to a receiving frequency to which the superheterodyne receiver (1) is tuned, said receiving frequency being dependent on said oscillator frequency (8) and said IF-carrier frequency (22);
a coupling system (33) having at least one input and coupled to said circuit arrangement to receive said HF-output signal (12), said coupling system coupling said HF-output signal (12) to the at least one receiving antenna (5) or a receiver input,so that the level of the receiving signal of the receiving installation (20) can be determined by said measuring system (10).
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Accused Products
Abstract
A circuit for testing the function of mobile radio receiving installations is provided, wherein the circuit generates an HF-output signal that is used to test the system. A frequency mixer receives an oscillation signal (8) generated from within the superheterodyne receiver and an IF-carrier oscillation signal (32) generated from and oscillator (7) within the circuit. The frequency mixer generates an HF-output signal (12) that is dependent on the amplitude and frequency of the received oscillation signals. In alternative embodiments of the invention, the circuit of the invention is incorporated into the superheterodyne receiver, and the generated IF-carrier frequency 32 is eliminated and replaced with an IF-signal 22 produced by self-excitation of the superheterodyne receiver. With multi-antenna scanning diversity systems, additional switches and switching signals are included.
125 Citations
14 Claims
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1. A circuit for testing the working function of a mobile receiving installation (20) having at least one receiving antenna (5) in a high frequency connection with a superheterodyne receiver (1), the superheterodyne receiver (1) having an image frequency filter (4), an oscillator (9), an IF-signal (11) and a measuring system (10) coupled to the IF-signal for detecting the level of the received signal, the circuit comprising:
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a circuit arrangement (2) disposed within the receiving installation (20) and coupled to the superheterodyne receiver (1) and the at least one antenna (5), said circuit arrangement comprising; a frequency mixer (3) having a first input coupled to an output of oscillator (9) in superheterodyne receiver (1), a second input and an output, oscillator (9) generating an oscillator signal (8); a feedback loop connecting the IF-signal (11) to said second input of said frequency mixer (3) to provide a self excitation condition, thereby generating an IF-carrier frequency (22), of limited amplitude from the IF-amplifier part of the superheterodyne receiver (1); said frequency mixer (3) producing an HF-output signal (12) having a constant amplitude with respect to time at its output, said HF-output signal (12) having a frequency conforming to a receiving frequency to which the superheterodyne receiver (1) is tuned, said receiving frequency being dependent on said oscillator frequency (8) and said IF-carrier frequency (22); a coupling system (33) having at least one input and coupled to said circuit arrangement to receive said HF-output signal (12), said coupling system coupling said HF-output signal (12) to the at least one receiving antenna (5) or a receiver input, so that the level of the receiving signal of the receiving installation (20) can be determined by said measuring system (10). - View Dependent Claims (2)
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3. A circuit for testing an RF superheterodyne receiver installation (20) over its reception band and coupled to at least one antenna (5), through a first RF connection line (14), for receiving an RF-receiving signal (13), the receiver (1) having an image frequency filter (4), a local oscillator (9), for producing a variable output signal (8) as the receiver is tuned, an IF-signal (11) and a measuring system (10) coupled to the IF-signal for detecting the level of the received signal, the circuit comprising:
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circuit arrangement (2) disposed within the receiver installation (20) and coupled to the superheterodyne receiver (1) and the at least one antenna (5), said circuit arrangement comprising; a second RF-connection line (23) connecting the superheterodyne receiver (1) with the circuit arrangement (2), said second RF-connection line (23) carrying said local oscillator signal (8) and the IF signal (11); a fixed frequency oscillator (7) for producing an IF-carrier frequency (32) approximately equal to the mean frequency of the IF-signal (11); a mixer (3) having its inputs coupled to the local oscillator (9) and fixed oscillator (7) for mixing the fixed and local oscillator signals (32 and
8) to produce an output signal 12 having a constant amplitude and a frequency conforming to a receiving frequency to which the superheterodyne receiver (1) is tuned, said receiving frequency being dependent on said fixed oscillator frequency (8) and said IF-carrier frequency (32);a coupling system (33) having at least one input coupled to said circuit arrangement (2) to receive said RF-output signal (12), a transmitting antenna (6) coupling said RF-output signal (12) to the at least one receiving antenna (5) said antenna being a low capacitive connection (21) so that the level of the receiving signal of the receiving installation (20) is determined by said measuring system (10), as the superheterodyne receiver (1) is tuned over its reception band. - View Dependent Claims (4, 5, 6, 7, 8)
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9. A circuit for testing an RF superheterodyne receiver (1) over its reception band having at least one receiving antenna (5), for receiving an RF receiving signal (13), the receiver (1) having an image frequency filter (4), a local oscillator (9), for producing a variable output signal (8) as the receiver is tuned, an IF-signal (11) and a measuring system (10) coupled to the IF-signal for detecting the level of the received signal, the circuit comprising:
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an RF connection line (14) coupling the antenna (5) to receiver (1); a first signal switch (16) disposed within the receiver (1) and coupled to the oscillator signal (8) and the IF-signal (11), said first signal switch (16) being coupled to a first end of said RF-connection line (14); a circuit arrangement (2) disposed within the receiver installation (20) and coupled through said RF connection line (14) to the superheterodyne receiver (1), and the at least one antenna (5), and wherein said local oscillator signal (8), the IF-signal (11) and the RF-receiving signal (13) are selectively transmitted across said RF-connection line (14), said circuit arrangement (2) comprising; a second signal switch (18) disposed within circuit arrangement (2) and coupled to the opposite end of said RF-connection line (14), said second signal switch (18) picking up IF-signal (11), a frequency mixer (3) coupled to said second switch (18) for receiving local oscillator signal (8); an amplitude limiter (17) coupled to second switch (18) for receiving IF-signal (11) and providing to mixer (3), an IF-signal (22), limited in amplitude, said mixer (3) producing an RF-output signal (12) at its output having a constant amplitude and a frequency conforming to a receiving frequency to which the superheterodyne receiver (1) is tuned, said receiving frequency being dependent on said fixed oscillator frequency (8) and said IF carrier frequency (11); a coupling system (33) having at least one input and coupled to said circuit arrangement to receive said RF-output signal (12), said coupling system coupling said RF-output signal (12) to the at least one receiving antenna (5) or a receiver input, wherein the RF-receiving signal (13) from antenna (5) is coupled to said second signal switch (18) and is transmitted across said RF-connection line (14) to said first signal switch (16) and coupled to the superheterodyne receiver (1), said first and second signal switches (16 and
18) being selected such that the signals on RF-connection line (14) do not interfere with each other,wherein the level of the receiving signal of the receiving installation (20) is determined by said measuring system (10), as the superheterodyne receiver (1) is tuned over its reception band. - View Dependent Claims (10, 11, 12)
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13. A circuit for testing an RF superheterodyne receiver (1) over its reception band having at least one antenna (5), for receiving an RF-receiving signal (13), superheterodyne receiver (1) having an image frequency filter (4), a local oscillator (9), for producing a variable output signal (8) as the receiver is tuned, an IF-signal (11) and a measuring system (10) coupled to the IF-signal for detecting the level of the received signal, the circuit comprising:
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an RF connection line disposed between said antenna (5) and said receiver (1); a circuit arrangement (2) coupled to line (14) between the antenna (5) and superheterodyne receiver (1) comprising; a mixer (3) having a first input for receiving frequency (8) of receiver (1), a second input for receiving an amplitude limited IF-signal (22); said frequency mixer (3) producing an RF-output signal (12) having a constant amplitude at its output, said RF-output signal (12) having a frequency conforming to a receiving frequency to which the superheterodyne receiver (1) is tuned, said receiving frequency being dependent on said fixed oscillator frequency (8) and said IF-signal (22); and wherein the receiving antenna (5) is an antenna scanning diversity system, and further comprises; a diversity processor (30) having a signal change-over switch (24) and a trouble indicator (25), said processor (30) being supplied with the IF-signal (11) from receiver (1), said RF-connection line (14) connecting said diversity processor (30) with the superheterodyne receiver (1); a coupling system (33) having at least one input to receive said RF-output signal (12), from said circuit arrangement (2), said coupling system coupling said RF-output signal (12) to the at least one receiving antenna (5), a switch signal generator (31) disposed within the superheterodyne receiver (1) and adapted to generate a switching signal (29), said diversity processor (30) being coupled with the IF-signal (11) and said switching signal (29) via the single RF-connection line (14), said switching signal (29) initiating the function test, so that the level of the receiving signal of the receiving installation (20) is determined by said measuring system (10), as the superheterodyne receiver (1) is tuned over its reception band. - View Dependent Claims (14)
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Specification