100 years of radio, the invention that saved the Eiffel tower

June 10, 2021.


On the occasion of the 100 years of the radio, we invite you to discover how to analyze FM radio and digital DAB radio signals using our RANGER Neo signal analyzers. A technology with nearly a century of history that had a major role to preserve one of the icons of Paris. Do you want to find out why? Keep reading...

Where in the spectrum are the FM radio and the digital DAB radio?

First, let's find out where we can find the FM channels and the digital DAB channels into the RF spectrum: The FM band covers the VHF spectrum from 87.5 to 108 MHz and the DAB spectral band uses the Band III from 174 to 240 MHz.

All PROMAX signal analyzers cover the terrestrial band from 5 to 950 MHz, therefore they can readily inspect the FM and DAB spectrums.

Where in the spectrum are the FM radio and the digital DAB radio
Where in the spectrum are the FM radio and the digital DAB radio

How to analyze an FM radio channel

This is what we are doing: Tuning an FM channel, analyze its measurements and then we will decode it:

  • Use the SPECTRUM ANALYZER 2/3 operating mode.
  • Tune by frequency (F1 key, "Tune by" option).
  • Move the cursor to an FM channel...
    • ... sliding the cursor using the touch screen.
    • ... or moving the joystick in "FR" mode.
    • ... or just typing its frequency (F1 key, "Frequency" option).
  • At this point, your meter automatically identifies the FM radio channel.
  • Increase the SPAN up to FULL SPAN (move the joystick to the right in "SP" mode).
  • Activate the "Max Hold" function (F4 key). The blue trace depicts the higher peaks, and it gradually expands thus allowing us to see the frequency modulation amplitude (50 Hz approx).
  • You can measure this amplitude using the "Marker" function (F4 key).

How to analyze an FM radio channel

Now you can measure and decode the FM signal. At the top of the screen you can see the signal level. You can listen to the live broadcast as long as the audio is activated in your equipment (long-press of the wheel key).

SIGNAL ANALYZERS WITH FM RADIO

How to analyze a DAB digital radio channel

This is what we are doing: Tuning a DAB channel, measure it and then we will decode it:

  • Use the SPECTRUM ANALYZER 2/3 operating mode.
  • Tune by frequency (F1 key, "Tune by" option).
  • Move the cursor to a DAB channel...
    • ... sliding the cursor using the touch screen.
    • ... or moving the joystick in "FR" mode.
    • ... or just typing its frequency (F1 key, "Frequency" option).
  • At this point, your meter automatically identifies the digital DAB radio multiplex.
  • Activate the Min Hold mode (F4 key) to analyze the small signal drops. You need an ultra fast spectrum analyzer such as RANGER Neo's to display these micro drops! The micro drops happen every 96 ms to synchronize the receivers. This is one among others signal DAB features to improve the signal reception of mobile receivers.

How to analyze a DAB digital radio channel

At the top of the screen you can see the signal level. You can listen to the live broadcast as long as the audio is activated in your equipment (long-press of the wheel key).

SIGNAL ANALYZERS WITH DIGITAL DAB RADIO

So, what can I do if my PROMAX analyzer has no digital DAB radio?

The DAB and DAB+ decoder is available for all RANGER Neo+ and above: The essential DAB/DAB+ functions are optional for the Plus and 2 models, being factory built in the 3 and 4 models. For the latter two models, the advanced DAB/DAB+ analysys functions are available as an option.

However, you can take power and C/N measurements even if you lack the DAB decoder:

  • Press F2 and select the "GENERIC" signal type.
  • Press F2 and manually set the DAB channel bandwidth (1536 kHz).
PROMAX signal analyzers integrate DAB analyzer
PROMAX signal analyzers integrate DAB analyzer either factory built or optionally (according to model)
SIGNAL ANALYZERS WITH DIGITAL DAB RADIO

It is well to remember that...

  • Radio stations are grouped in the so called ensemble or multiplex. A multiplex is a digital data stream transmitted by a DAB broadcaster in a given frequency. En emsenble may contain from 9 up to 12 DAB programmes or from 18 up to 32 DAB+ programmes.
  • The modulation used is DQPSK-type (Differential Quad Phase Shift Keying) processed with OFDM, that provides a good immunity against attenuation and intermodulation interferences caused by signal reflections (echoes). This modulation is specially conceived to be used in mobile telecommunications.
  • In terrestrial mode, OFDM modulation is composed of 1536 carriers with a channel bandwidth of 1536 kHz.
  • Using a guard interval allows its use in SFN networks, where all transmitters broadcast using the same frequency.

DQPSK constellation of a DAB signal with a RANGER Neo+ analyzer

How did the radio save the Eiffel Tower?

In the middle of a great social controversy (it was said it deformed Paris architectonic harmony), the most known work of Gustave Eiffel was erected on the occasion of the 1889 Universal Exhibition in Paris. Its disassembling was planned for 20 years later.

However after the outbreak of WWI, the tower demonstrated to be a key structure to intercept the communications of the enemy and to be used as communications position for the French army. Actually, before the outbreak of the war, the tower had been used on an experimental basis to broadcast wireless communications.

The use as telephony and radio prevented the Eiffel tower to be disassembled
The use as telephony and radio prevented the Eiffel tower to be disassembled

The military use first, and the later use as telephony and radio tower, prevented the disassembly of the Eiffel tower allowing it to reach our days housing 120 antennas, 32 radio stations and 40 television channels.

Share :

PROMAX is a leading manufacturer of test and measurement systems, broadcast and TV signal distribution equipment. Our product lines include measuring instruments for cable TV, satellite TV, broadcast, wireless and fibre optics networks, FTTH and GPON analyzers. DVB-T modulators, IP streamers or IP converters (ASI, DVB-T) are among the company’s latest developments.