DE102008024248A1 - Field strength profiles generating method for reception-testing of mobile radio receiver i.e. car radio, involves measuring, filtering and statistically modeling field strength distributions of transmitter frequencies - Google Patents

Abstract

The method involves measuring, filtering and statistically modeling field strength distributions (FV1-FV4) of transmitter frequencies (SF1-SF4), where the filtering is carried out by a low-pass filter of second order and the modeling is carried out by logarithmic normal distribution and Rayleigh distribution. The field strength distributions are divided into two individual distance sections. Parameters concerning minimum and maximum field strengths and difference of the minimum and maximum field strengths are determined for each distance section of the field strength distributions.

Description

Technical area

The The invention relates to a method for generating field strength profiles for reception testing of mobile radio reception equipment, for example Car radios, under laboratory conditions.

State of the art

From the DE 10 2006 032 270 A1 a method for testing a mobile radio receiving device under laboratory conditions is known, wherein the radio receiving device signal-carrying radio waves with a predetermined frequency and field strength (a radio field profile was obtained in advance by field measurements and / or simulation calculations) exposed and a power-determining output of the radio receiving device is detected and evaluated.

The Radio receiving device is in a time-consuming test program with the radio waves of a pre-stored field strength-time curve applied and the output as a function the field strength measured.

Becomes a radio field profile obtained by field measurements, so the field strength curve, for example as a result of shadowing or multipath propagation, be exposed to various fading influences.

Object of the invention

Of the Invention is the object of providing a method for the reproduction of lost fading effects under real conditions measured field strength gradients based.

Solution of the task

The Task is achieved by a method according to claim 1 solved.

Advantages of the invention

Around in a test of mobile radio receivers, for example Car radios, under laboratory conditions largely real environmental conditions to reproduce reproducibly be under real Conditions field strength gradients of different Transmission frequencies, such as a radio station, measured, filtered and statistically modeled.

Of the Field strength profile obtained by measurement and filtering does not take into account any lost progressions, especially from fading. Their replication will be the previous field strength course Statistically modeled field strength gradients are added up.

Of the from the summation of the filtered field strength curve and the statistically modeled field strength curve Field strength course forms at least partially an inventive field strength profile.

Based the resulting field strength gradients can Laboratory tests of mobile radio reception equipment, for example Car radios, are performed so that by means of laboratory results objective quality assessments can be achieved. In the laboratory tests, the individual field strength gradients parallel in time, staggered or played in succession.

With the method of the invention can with a relatively low metrological effort, the reception conditions recorded along a considered route and for playback in the Laboratory be prepared.

to Playback in the laboratory are basically the possibilities the direct recording and reproduction of the recorded data and the modeling of reception conditions by statistical means to disposal. In the present process is a mixture applied both methods, whereby the respective advantages of both Procedures are taken into account.

In an advantageous embodiment of the invention will the field strength course continuously or discontinuously measured. Possible criteria for selecting a Measurement mode (continuous or discontinuous) can the amount of data, the degree of compression of the "required" field strength values, the measuring technology as well as special features of the measured test track be.

at the method of the invention can both continuous and discontinuous Measurement only individual values (interpolation points) of the measured Field strength values are used. The criteria for Support point selection can be determined individually can and can vary according to the characteristics of the received signal judge. Example of this can be a dense sequence of supporting values be in areas that have a high spatial resolution while in areas with relatively constant receive signal characteristics lower interpolation rate is necessary.

The conditioning of the measured field strength profiles comprises a filtering by means of low-pass filtering of the second order. By means of low-pass filtering An antialiasing of the field strength profile can be achieved.

In an advantageous embodiment of the invention will the measured field strength course by means of a logarithmic Normal distribution and a subsequent Rayleigh distribution statistically modeled.

through the logarithmic normal distribution is a replica of Shadowing, so-called "slow fading". The local Resolution should be one for effects of "slow fadings "typical value of about 10 m. The subsequent Rayleigh distribution replicates multipath propagation caused so-called "almost fading". The local Resolution of this modeling should also be a typical Value, here for effects of "almost fading", accept. This value is in the range of half the wavelength of the considered frequency range, ie for example at 1.67 m for an FM frequency of 100 MHz. In the considered scenario of FM broadcasting, Doppler effects are within the coherence frequency and therefore play a negligible role.

In mark an advantageous embodiment of the invention the above measured support values individually considered sections of the test track.

For each section of track becomes individual field strength parameters certainly. Provide examples of corresponding parameters the minimum and maximum field strength, in addition to that Outliers can be refined, and the resulting outliers Fluctuation range (difference between minimum and maximum field strength) represents.

The Classification of outliers can be, for example, by Determination of a range of field strength distribution within of a section of the route, 66% of the total detected field strength values recorded. Ordinary field strength values then lie within this range and outliers outside thereof.

The Choice of area may depend on the desired Test situation done.

In an advantageous embodiment of the invention the field strength parameters of a statistical modeling subjected.

advantageously, For each segment, the parameter of the minimum Field strength low-pass filtered and the fluctuation range (Difference between the maximum and minimum field strength) statistically modeled.

Instead of The fluctuation range can be the maximum field strength statistically be modeled.

Provided a division of the field strength course into "normal" field strength values and "outliers" done, the low-pass filtering and the statistical modeling done accordingly for the "outliers".

Around a field strength course according to the invention to achieve the field strength values of low pass filtering and the statistical modeling summed up.

drawings

It demonstrate:

1 a section of a measured field strength curve of a radio transmitter with different transmission frequencies with co-channel interference;

2 : a section of the measured field strength profile of a transmission frequency with interpolation points;

3 : the field strength history 2 with sections and parameters;

4 : the field strength history 3 after a second-order low-pass filtering;

5 : the field strength history 3 after a statistical modeling by means of a logarithmic normal distribution;

6 : the summed field strength curve from the 4 and 5 after a statistical modeling by means of a Rayleigh distribution;

7 : a section of a field strength profile.

In 1 a section of measured field strength curves FV1, FV2, FV3, FV4 of a radio transmitter RS with three different transmission frequencies SF1, SF2, SF4 along a distance S is shown. There is also a foreign radio station, which sends its SF3 frequency on the same frequency as RS (SF2 = SF3) and thus causes a co-channel interference GK. The field strength profiles FV1, FV2, FV3, FV4 were recorded during a test drive in rural areas, for example. The individual field strength curves FV1, FV2, FV3, FV4 were measured discontinuously. Each measured field strength value forms a support point, which in 2 are shown.

Due to low transmission power of the individual transmission frequencies SF1, SF2, SF3, SF4 occur frequent alternative frequency changes AF. Furthermore, in the illustrated field strength curves FV1, FV2, FV3, FV4, the above-mentioned co-channel interference GK can be recognized by a foreign radio station and losses of all alternative frequencies AFV for a specific time period.

basis for the creation of field strength profiles (datasets) can form test drives, using GPS data and a video be used with the filmed display of a reference radio. The Car radio can be operated in test mode to the currently received Field strength F can be read.

The 2 shows the field strength curve FV1 for the transmission frequency SF1 according to 1 , The measurement of the field strength profile FV1 was carried out discontinuously and depending on the conditions in the section part, so that each measured value forms a support point ST1, ST2.

In the 3 is the field strength curve FV1 off 2 divided into sections SA1, SA2 shown. The in the 3 shown sections SA1, SA2 are not equidistant and result from the in 2 marked three adjacent support points.

For each section SA1, SA2 becomes field strength parameters determined. For the determination, the during the measurement run recorded data for field strength course FV1 used within the considered track section SA1, SA2, possible parameters are the minimum field strength Fmin and the maximum field strength Fmax. From both parameters the difference ΔF can be formed as a further parameter.

Farther there is the possibility of that in each section of the route Classify SA1, SA2 field strength values.

The Classification can be for the whole field strength course FV1 or separately for each section SA1, SA2 respectively. By means of the classification, field strength value ranges are formed after which field strength values outside this Area B are located, are declared as so-called outliers.

In the 3 the range is approximately 66% of the total field strength value range in the considered section SA1, SA2. This means that for the section SA1 (or in total) the minimum field strength Fmin and the maximum field strength Fmax are determined. Their difference ΔF is set as 100%. A region B is formed around the determined mean value, which covers 2/3 of all occurring field strength values. All field strength values that are larger or smaller than the 2/3 range B are assigned to the outliers. In 3 an outlier of a maximum field strength FmaxA is shown in the section SA2.

The 4 shows the field strength curve FV1 after a low-pass filtering TP second order. The low-pass filtering TP is based on the parameters minimum field strength Fmin and minimum field strength outliers for each line segment SA1, SA2. The field strength curve FV1 on which the low-pass filtering TP is based forms on the one hand the minimum field strength Fmin (a minimum field strength Fmin for each route segment SA1, SA2) which are expanded according to the respective route length and on the other hand the minimum field strength values outliers (a minimal field strength value for each route segment SA1, SA2) Outliers), which are expanded according to the respective route length.

is For example, in the first section SA1, in the area between 0 and 800 meters, the minimum field strength value is Fmin 35 dBμV and in the second section SA2, in the range greater than 800 meters and 1000 meters is the minimum Field strength value Fmin 40 dBμV, so the resulting Field strength curve FV1 in the range between 0 meters and 800 Meter is 35 dBμV (minimum field strength value Fmin in the first section SA1) and larger in the area 800 meters and 1000 meters the value 40 dBμV (minimum field strength value Fmin in the second section SA2).

In 5 the field strength course FV1 is shown according to a statistical modeling by means of a logarithmic normal distribution logN. For this modeling, each section of the route is subjected to an equidistant division, which is based on the effects typical of "slow fading" and thus enables a local resolution of the modeling of, for example, 10 m. For this purpose, the in 3 shown differences .DELTA.F from minimum field strength Fmin and maximum field strength Fmax based. Alternatively, for the statistical modeling of the parameter maximum field strength Fmax can be used.

In 6 is the in 5 shown field strength course FV1 according to a statistical modeling with a Rayleigh distribution RY shown. For this modeling, each section of the track is subjected to a further finer equidistant division, which is based on the effects typical for "fast fading" and thus enables a local resolution of the modeling of half the wavelength of the frequency range used (for example, 1.67 m at 100 MHz). , For a statistical modeling using Rayleigh distribution RY be likewise the in 3 shown differences .DELTA.F from minimum field strength Fmin and maximum field strength Fmax based. Alternatively, for the statistical modeling of the parameter maximum field strength Fmax can be used.

7 shows an inventive field strength profile FP of a radio station RS. This field strength profile FP is based on the in 1 shown field strength curves FV1, FV2, FV3, FV4. In the 7 shown field strength curves FV1, FV2, FV3, FV4 result from the summation of the low-pass filtered field strength profile TP ( 4 ) and of the statistically modeled (by means of a logarithmic normal distribution logN ( 5 ) and a Rayleigh distribution RY ( 6 )) Field strength course of FV1.

The in the 7 shown field strength curves FV1, FV2, FV3, FV4 are arranged one behind the other or partially in parallel.

Dependent from the desired test situation can in one Field strength profile FP the respective number and arrangement the field strength curves FV1, FV2, FV3, FV4 vary.

AF

Alternatively, frequency change

AFV

Alternatively frequency loss

B

Area

F

field strength

fmin

minimum field strength

Fmax

maximum field strength

FmaxA

maximum Field strength outliers

FP

Field strength profile

FV1

Field strength curve

FV2

Field strength curve

FV3

Field strength curve

F4V

Field strength curve

GK

Co-channel interference

log N

logarithmic normal distribution

RS

radio stations

RY

Rayleigh

S

route

SA1

stretch

SA2

stretch

SF1

transmission frequency

SF2

transmission frequency

SF3

transmission frequency

SF4

transmission frequency

ST1

support point

ST2

support point

ST3

support point

TP

Low-pass filtering

.DELTA.F

difference

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102006032270 A1 [0002]

Claims (12)

Method of creating field strength profiles (FP) for reception testing of mobile radio receivers under Laboratory conditions, whereby a field strength profile (FP) at least one dependent on the distance (S), the time and the speed Field strength course (FV1, FV2, FV3, FV4) for at least a transmission frequency (SF1, SF2, SF3, SF4), and the field strength course (FV1, FV2, FV3, FV4) is measured, filtered and statically modeled. Method according to claim 1, characterized in that that the measurement takes place continuously. Method according to claim 1, characterized in that that the measurement is discontinuous. Method according to claim 1, characterized in that that the filtering by means of low-pass filtering (TP) second order he follows. Method according to claim 1, characterized in that that the static modeling by logarithmic normal distribution (logN) and Rayleigh distribution (RY). Method according to at least one of the preceding Claims, characterized in that the measured field strength course (FV1, FV2, FV3, FV4) in at least two separate sections (SA1, SA2) is divided. Method according to Claim 6, characterized that for each section (SA1, SA2) of the measured Field strength curve (FV1, FV2, FV3, FV4) parameters with regard to the minimum field strength (Fmin) and the maximum field strength (Fmax) and the resulting difference (ΔF) become. Method according to claim 7, characterized in that that in addition parameters with regard to the minimum field strength and the maximum field strength (FmaxA) of field strength values, outside a range (B) of the field strength values lie in the respective route section (SA1, SA2), and the resulting difference are determined. Method according to claim 7 or 8, characterized that the parameter difference (.DELTA.F), the minimum field strength (Fmin) and maximum field strength (Fmax) are formed, be statistically modeled. Method according to claim 9, characterized that the parameter difference (.DELTA.F), the minimum field strength (Fmin) and maximum field strength (Fmax) are formed, by logarithmic normal distribution (logN) and subsequent Rayleigh distribution (RY) can be statistically modeled. Method according to claim 7 or 8, characterized that the parameters minimum field strength (Fmin) by means of a Low-pass filtering (TP) of the second order can be filtered. Method according to claims 10 and 11, characterized the values of the filtered field strength profile (FV1, FV2, FV3, FV4) and the statistically modeled field strength curve (FV1, FV2, FV3, FV4) are summed.