Patent Application
20050260963
Not applicable
This invention relates generally to radio receiver testing, and more particularly to a method and system for a radio receiver system wideband self test.
Creating a radio receiver self test requires generating RF signals at all channels of operation. A conventional solution requires signal generators based on frequency stabilized VCOs and PLL circuits. To cover all the desired frequency bands, a conventional system would also require multiple VCOs. Such a test set-up with multiple VCOs likely exists in many manufacturing sites for testing radio receivers. Multiple VCOs on a radio receiver itself for testing purposes would unnecessarily increase the cost of a portable subscriber unit. Currently, no simple low cost solution exists for generating a broadband signal within a radio receiver unit for purposes of self-testing the receiver. Nor does a low-cost self-test exist that covers all radio channels, particularly in a broadband receiver.
A receiver system and method for wideband self-test can provide a mobile/cellular phone with a receiver self test that operates over the all radio bands. The radio receiver self test system can test all the present day and future bands in duplex (CDMA, TDMA, GSM, iDEN, etc.) cellular phones or other duplex communication devices having transceivers. The self test system can be constructed to operate during idle time slots for a given protocol such as in time slots for CDMA or TDMA transmissions. The system can be configured to test the performance of the radio receiver at all ranges of signal levels and in all channels and can also be configured to test the performance of receiver subsystems for present day and future bands for all cellular phones. The circuitry for such self-test can be integrated using standard IC processes. Such a system can provide a broadband signal at low cost using thermal noise and broadband amplifiers.
In a first embodiment of the present invention, a wideband self-testing receiver system can include a receiver, a broadband noise source, an antenna/noise switch selectively coupled between the broadband noise source and the receiver, and a processor coupled to the antenna/noise switch and the broadband noise source. The broadband noise source can include an excess noise amplifier chain that generates noise power proportional to an amplifier gain and the excess noise amplifier chain can include an excess noise amplifier designed to be broadband, have a high noise factor, and a bandwidth exceeding the highest frequency of operation for the receiver. Alternatively, the broadband noise source can include a bank of amplifiers tuned to cover separate bands of operation for the receiver.
The processor can be programmed to control the gain level of the broadband noise source and to control the antenna/noise switch for routing noise from the broadband noise source to an appropriate receiver chain to enable the wideband self-testing receiver system to perform a self-test. The receiver can be a portion of a duplex CMDA or TDMA transceiver and the self-test can occur during at least one idle time slot such as a CDMA or TDMA time slot. The system can further include an antenna coupled to the receiver. The processor can be further programmed to test the performance of the receiver at substantially all ranges of signal levels and in substantially all channels available. The processor can also be programmed to alternatively introduce a known level of noise into a front end of the receiver, detect and measure a signal strength as the front end processes the known level of noise, and compare the signal strength measured with a stored value. Additionally, the processor can be programmed to perform a self-test on an automatic gain control circuit and to generate a diagnostic report via at least one among a radio channel, an infrared port, or a cabled connection to the processor.
In a second embodiment of the present invention, a method of self testing a duplex radio receiver can include the steps of selectively coupling a broadband noise source into a receiver chain and controlling the gain level of the broadband noise source to introduce a known level of noise into a front end of the receiver, detect and measure a signal strength as the front end processes the known level of noise, and compare the signal strength measured with a stored value. The controlling step can occur during at least one idle time slot such as during an idle CDMA or TDMA time slot. The method can further include the step of generating noise power proportional to an amplifier gain. The method can further include the step of testing the performance of the receiver at substantially all ranges of signal levels and in substantially all channels available. Additionally, the method can further include the step of generating a diagnostic report via at least one among a radio channel, an infrared port, or a cabled connection to the processor.
In a third embodiment of the present invention, a computer program can have a plurality of code sections executable by a machine for causing the machine to perform the steps of described in the embodiment above.
Referring to
The self test system can start with a noise source 18 created using an Excess Noise Amplifier chain for example. The Excess Noise Amplifier chain can generate excess noise power proportional to the amplifier gain as shown below:
Pself_test=F*kT*BW*Gain (Watt)
Were: F=Amplifier Chain Noise Factor
The Excess Noise Amplifier can be designed to be broadband and have a high noise factor (F). The bandwidth of the Excess Noise Amplifiers can exceed the highest frequency of operation of the radio. Alternatively, banks of amplifiers tuned to cover separate bands are also contemplated herein.
The Excess Noise Amplifier gain can be controlled by a BB Noise Source level control (27) which acts as an Excess Noise AGC circuit. The gain control mechanism in the Excess Noise AGC circuit can be a programmable current source that sets the bias level of the amplifier chain. The gain level of the Excess Noise AGC can be controlled by a base processor (24) which programs the Excess Noise AGC via an Excess Noise Control bus.
The noise output of the Excess Noise Amplifier can be fed into the radio receiver front end via the Antenna/Noise Switch 16. A TR/RX/AGC Test control signal 26 is used to enable the switch and route the noise into the appropriate receiver chain.
The output of the Excess Noise Amplifier (18) can produce broadband noise from a few dB above the sensitivity threshold of the system to as high as 60 dB or more above the noise floor. The output level of the Excess Noise Amplifier can be controlled in steps of a few dB as desired. The performance and trigger points of the radio's own AGC can be checked with this self test by adjusting the output levels of the Excess Noise Amplifier 18 and comparing the curve with expected values. The radio's processor (24) can be programmed with software to perform a self test routine which can be performed during idle time slots.
Referring to
As shown, the system 30 can include multiple receive and transmit paths or chains. A first receive path 36 can include an amplifier 33 coupled between SAW filters 31 and 35 and a second receive path 46 can include an amplifier 43 coupled between SAW filters 41 and 45. Each of the receive paths can also include a mixer 38. A first transmit path can include a mixer 48 and an amplifier 37 while a second transmit path can include the mixer 48 and another amplifier 39.
As in the prior example of system 10 of
Pself_test=F*kT*BW*Gain (Watt)
The noise source 40 can use an Excess Noise Amplifier 50 designed to be broadband and have a high noise factor (F). The bandwidth of the Excess Noise Amplifiers can exceed the highest frequency of operation of the radio. Alternatively, banks of amplifiers tuned to cover separate bands are also contemplated herein.
The Excess Noise Amplifier gain can be controlled by the control signal 51 serving as an excess noise control signal for a programmable current source 54 which acts as an Excess Noise AGC circuit. The current source 54 can be powered by a power source 52 such as a battery. The gain control mechanism in the Excess Noise AGC circuit can use the programmable current source 54 to set the bias level of the amplifier chain. The gain level of the Excess Noise AGC can be controlled by the processor 34 which can program the Excess Noise AGC via an Excess Noise Control bus (51).
The noise output of the Excess Noise Amplifier can be fed into the radio receiver front end via the T/R Switch 32. The self-test switch control signal 53 is used to enable the switch and route the noise into the appropriate receiver chain.
The output of the Excess Noise Amplifier (50) can produce broadband noise from a few dB above the sensitivity threshold of the system to as high as 60 dB or more above the noise floor. The output level of the Excess Noise Amplifier can be controlled in steps of a few dB as desired. The performance and trigger points of the radio's own AGC can be checked with this self test by adjusting the output levels of the Excess Noise Amplifier 50 and comparing the curve with expected values. The radio's processor (34) can be programmed with software to perform a self test routine which can be performed during idle time slots.
In yet another embodiment as shown in
As in the prior examples of systems 10 and 30 of
Pself_test=F*kT*BW*Gain (Watt)
The noise source 88 can use an Excess Noise Amplifier designed to be broadband and have a high noise factor (F). The bandwidth of the Excess Noise Amplifiers can exceed the highest frequency of operation of the radio and injects broadband noise in all the intermediate frequency (IF) bands in the subsystem. Alternatively, banks of amplifiers tuned to cover separate bands are also contemplated herein.
The Excess Noise Amplifier gain can be controlled by a broadband noise source level control signal from the processor 86 which can serve as an excess noise control signal for a programmable current source (not shown) which acts as an Excess Noise AGC circuit. The gain control mechanism in the Excess Noise AGC circuit can use the programmable current source to set the bias level of the amplifier chain. The gain level of the Excess Noise AGC can be controlled by the processor 86 which can program the Excess Noise AGC via an Excess Noise Control bus.
The noise output of the Excess Noise Amplifier can be fed into the radio receiver front end via the subsystem select switch 87. The processor 86 can be a baseband upconverter/downconverter that provides a subsystem test control signal to enable the subsystem select switch 87 and route the noise into the appropriate subsystem in the receiver chain.
The output of the Excess Noise Amplifier can produce broadband noise from a few dB above the sensitivity threshold of the system to as high as 60 dB or more above the noise floor. The output level of the Excess Noise Amplifier can be controlled in steps of a few dB as desired. The performance and trigger points of each subsystem AGC can be checked with this self test by adjusting the output levels of the Excess Noise Amplifier and comparing the curve with expected values. The radio's processor (86) can be programmed with software to perform a self test routine which can be performed during idle time slots.
This self test can introduce a known level of noise into the front end of the receiver. The level of the noise as it processed by the radio through its front end can be detected and measured using for example a signal strength indicator such as RSSI (see
Referring to
In light of the foregoing description, it should be recognized that embodiments in accordance with the present invention can be realized in hardware, software, or a combination of hardware and software. A receiver system and self testing arrangement or device according to the present invention can be realized in a centralized fashion in one computer system or processor, or in a distributed fashion where different elements are spread across several interconnected computer systems or processors (such as a microprocessor and a DSP). Any kind of computer system, or other apparatus adapted for carrying out the functions described herein, is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the functions described herein.
Additionally, the description above is intended by way of example only and is not intended to limit the present invention in any way, except as set forth in the following claims.
