Method for correcting testing equipment, and equipment

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method of calibrating the frequency of a test device or test device for testing a mobile terminal provided to operate in a mobile communication network such as a mobile phone or cellular phone.

【0002】

[Conventional technology]

Such methods and test instruments are known from the German technical journal "Funkschau" 1997, No. 16, pp. 64-66, R. Schoblick's paper "Mcβ technik fur GSM-Mobiltelefone". Such test equipment used to test the basic functions and specifications of mobile phones or cellular phones when manufacturing mobile phones, at the final control of the manufacturing process, or when discovering defects in defective mobile phones A very accurate internal reference frequency must be included to sample or measure radio frequency (HF) or radio frequency (RF) parameters required for data transmission operations.

【0003】

However, the corresponding reference frequency oscillator incorporated in the test apparatus may deviate or deviate from a desired frequency due to the effect of aging or the influence of temperature. Therefore, recalibration of this desired frequency is sometimes necessary. In fact, recalibration is needed almost every year. For this reason, there is a need for an extremely accurate external reference frequency device that is costly due to the high accuracy required. In particular, small stores and service stations do not have the financial means needed to own such a reference frequency device. However, even if such reference frequency equipment is readily available, standard external frequencies are used in the test equipment to ensure that the test equipment is within the acceptable range required for the measurement of radio frequency parameters. The correlation of the actual frequency with the desired desired frequency must be continuously confirmed. However, this is also extremely time consuming. On the other hand, if you use a test device that deviates from the desired frequency and you are not aware of it, the mobile phone you are testing will be misaligned during final control or when testing the mobile phone. In some cases, for example, reception quality or transmission quality may deteriorate.

【0004】

[Problems to be Solved by the Invention]

Therefore, it is an object of the present invention to improve the aforementioned method so that the desired frequency of the test device can be self-tested at any time and calibrated in a rapid and highly accurate manner.

【0005】

Another object of the present invention is to calibrate test equipment "for free" using the unique and inherent frequency accuracy of mobile networks.

【0006】

Another object of the present invention is to calibrate the test equipment without the use of expensive reference frequency equipment or counters. Also, the test equipment does not need to be sent to the manufacturer for calibration.

【0007】

Yet another object of the present invention is to apply a test method that can be used anywhere that can communicate with a (wireless) telecommunications network. This means that mobile phone test equipment can be used almost anywhere. In that respect, the communication network may be any suitable communication network, in particular, GSM (global system for mobile communication) or PCN / PCS (personal communication net). Mobile communication system).

【0008】

[Means for solving problems]

An object of the present invention is that the test device passively listens to or intercepts the established communication by the data connection established between the mobile terminal and the mobile communication network, and the test device at least receives the information signal underlying the communication. This is achieved by partially sampling and evaluating, and based on this evaluation, calibrating the reference frequency built into the test equipment.

【0009】

Thus, in the prior art, the test device is used to communicate with the mobile phone being tested, i.e. to exchange data, as opposed to the present invention. That is, the test device according to the present invention monitors or intercepts data exchange between a mobile phone and a communication network, particularly a base station, a telecommunications satellite, etc. in an interception mode or a listening mode, and is based on information signals generated sequentially. It is characterized in that the corresponding time and frequency reference are acquired as a calibration means and adjusted or compared with the internal reference frequency. The internal reference frequency is the central clock for all measurements. The actual calibration can be done manually or automatically by implementing appropriate software that minimizes the measured frequency error of the mobile phone. In that respect, for example, in frequency calibration, only the burst frequency is required, so it is only necessary to partially monitor the communication. Therefore, it is not necessary to use an expensive reference frequency device.

【0010】

A preferred embodiment of the method according to the invention is to process a bitstream that periodically returns in the time domain as an information signal, from a mobile terminal where the test equipment establishes a data connection as a bitstream. It is to analyze the burst of the test equipment and realize an accurate frequency reference of the test equipment.

【0011】

According to another preferred embodiment of the invention specifically adapted for measurement, bursts are analyzed by a test instrument in asynchronous test mode of the call channel.

【0012】

It is preferable that the burst emitted from the mobile phone has a predetermined frequency defined by the base station and the corresponding mobile phone communication standard in the following cases. That is, it is the initial synchronization between the mobile terminal and the base station until a data exchange between the mobile terminal and the base station is (passively) heard after a pre-rise or a transition period of a few seconds. It is when the stage is waiting.

【0013】

For this purpose, the process of reserving a mobile terminal, especially a mobile phone or cellular phone, initiates communication between the mobile phone and the corresponding base station in order to establish data communication between the mobile terminal and the base station. In order to do so, the mobile terminal is initialized and reserved.

【0014】

According to a preferred embodiment, the test equipment uses a power divider to passively listen to the communication and is coupled to an established communication link for communication between the mobile phone and the corresponding base station. Intercept the underlying electromagnetic field.

【0015】

Alternatively, the test equipment can also be coupled to an established communication link using an antenna or antenna element located near the mobile terminal.

【0016】

Also, according to the aforementioned object, the present invention provides a test device including a switchable passive interception mode or listening mode in which the test device samples and analyzes data exchange between a mobile terminal and a base station. It will be solved by. For this purpose, interception or listening mode test equipment inspects the frequency accuracy of the reference frequency unit by comparing the signal from the reference frequency unit contained in the test equipment with the information signal underlying the monitored data exchange. Includes calibration function to calibrate.

【0017】

In contrast to conventional testing equipment, which includes only an active mode of operation for performing functional tests on mobile phones and therefore requires calibration using expensive precision frequency equipment for frequency calibration of the internal reference frequency. The test equipment according to the present invention further comprises a passive mode capable of utilizing a frequency reference defined by an information signal exchanged between a mobile terminal and a corresponding base station.

【0018】

According to a preferred embodiment of the present invention, inspection and calibration are performed using a real-time graphic display device, thereby eliminating the need for an additional visual aid device such as an oscillograph for adjustment. In this way, for calibration of the test equipment, the frequency error of the sampled bursts can be continuously monitored and adjusted, for example, especially manually.

【0019】

Yet another preferred embodiment of the invention is disclosed in a dependent claim.

【0020】

Hereinafter, the present invention and its features, purposes, advantages and uses will be described with reference to the accompanying drawings. In that respect, all single features or any conceivable combinations described and / or illustrated constitute the subject matter of the invention, regardless of the claims or their dependents.

【0021】

BEST MODE FOR CARRYING OUT THE INVENTION

The method according to the invention is schematically shown in its essential process steps in the flowchart shown by reference numeral 10 in FIG. In the first process step 11 of Flowchart 10, the mobile terminal, which is a mobile phone or cellular phone in a preferred embodiment, is initialized by switching the mobile phone or cellular phone and making a reservation or registering with the communication network, respectively. Connection to the mobile communication network is established. Connections are realized on call channels, such as data connections, SMS messages, conversations, and so on.

【0022】

In the second process, stage 12, the mobile phone meets telecommunications standards, especially the ETSI (European Telecommunication Standards Institute) standard for GSM mobile telecommunications networks, after an initial rise period of a few seconds. Δv / v 10^-7It waits for the initial synchronization stage to synchronize with the locally assigned base station with extremely high accuracy, which is more accurate than. In that respect, the base station has Δv / v10.^-9Has better frequency accuracy than.

【0023】

Further in process stage 13, the test equipment according to the invention is coupled to communication between the mobile phone and the base station using a power divider, or antenna located near the mobile phone. At this stage, the test equipment is switched to passive listening mode.

【0024】

In asynchronous test mode, in the next process step 14, bursts emitted from mobile phones in the call channel are measured and analyzed by the test equipment. Test instrument measurements indicate the frequency error of these bursts on a monitor or screen. The accuracy of the emitted burst is guaranteed by the ETSI standard and is usually Δv / v 5 * 10^-8Or because it is in a higher range, the frequency error of this burst depends only on the accuracy (inaccuracy) of the test equipment. The frequency reference of the test system determines the reception frequency of the tester by the principle of frequency synthesis. The measured frequency error is zero only if the received frequency of the tester is equal to the frequency of the mobile phone. Therefore, each change in the frequency reference of the tester causes different measured values of frequency error. If the frequency error is "zero", the tester's frequency reference is tuned to the accuracy of the telecommunications network.

【0025】

In the next process stage 15, the reference crystal oscillator of the test equipment is mechanically or electrically adjusted until the display frequency error of the burst emitted from the mobile phone is at its minimum, and in the final process stage 16, the test equipment Is calibrated. In this case, the reference crystal oscillator should be sufficiently accurate as provided by the base station.^-7Has higher accuracy than. This accurate frequency reference of the tester can then be used for other calibrations such as counters and analysis.

【0026】

The present invention has been described using its preferred embodiments. However, it is clear to the expert that various changes and modifications can be made without departing from the scope and gist of the invention. In particular, the use of the intrinsic frequency accuracy of mobile telecommunications networks to calibrate mobile or cellular telephone test equipment is the same as the essential idea of the present invention. Therefore, a "mobile phone" can also be integrated or incorporated into the test equipment. Of course, when performing the method according to the invention, it is necessary to operate in the mobile network before actually calibrating the frequency, especially by establishing a connection between the test equipment used for the calibration and the mobile phone. Can test the specifications of mobile phones. It seems to be particularly important that the accuracy of the mobile phone's transmitter frequency is "read" by test equipment that is conventionally used only for communication with the mobile phone. This allows the tester's reference frequency to be "indirectly" (via a mobile phone) adjusted to the exact frequency of the base station.

[Simple explanation of drawings]

[Figure 1]

A flowchart showing the essential process steps of the method according to the invention is shown.