Accessories:External Filters - Revision history

imported>Dl4mea: /* The Filters */

2013-11-15T16:34:34Z

The Filters

← Older revision		Revision as of 16:34, 15 November 2013
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	{\| class="wikitable"		{\| class="wikitable"
	\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|thumb\|1090 MHz 3 Pole Filter (with two N female connectors)]]		\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|thumb\|1090 MHz 3 Pole Filter (with two N female connectors)]]
	\|[[File:5pole filter-4-resized.jpg\|500px\|1090 MHz 5 Pole Filter]]		\|[[File:5pole filter-4-resized.jpg\|500px\|thumb\|1090 MHz 5 Pole Filter]]
	\|-		\|-
	\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz		\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz

imported>Dl4mea: /* The Filters */

2013-11-15T16:34:14Z

The Filters

← Older revision		Revision as of 16:34, 15 November 2013
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	{\| class="wikitable"		{\| class="wikitable"
	\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|1090 MHz 3 Pole Filter ]]		\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|thumb\|1090 MHz 3 Pole Filter (with two N female connectors)]]
	\|[[File:5pole filter-4-resized.jpg\|500px\|1090 MHz 5 Pole Filter]]		\|[[File:5pole filter-4-resized.jpg\|500px\|1090 MHz 5 Pole Filter]]
	\|-
	~~\|''The 3 pole filter (both ports N female)''~~
	~~\|''The 5 pole filter''~~
	\|-		\|-
	\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz		\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz

imported>Dl4mea: /* Basics */

2013-11-14T21:27:39Z

Basics

← Older revision		Revision as of 21:27, 14 November 2013
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	~~==Basics==~~

	Most of us do live in an area where they are not alone. Many transmitters are around us, not just those that we really want to receive. It is then the task of the receiver to make a selection of the radio spectrum that is actually of interest. This is done with filters at the input. Unfortunately, for the radar signals on 1090 MHz, such filters are either large or do have significant attenuation, usually 3dB (half of the signal is lost).
	I decided not to put any filter at the input but instead use a proven high IP (Intercept Point) device directly at the input, which is significantly more robust against out-of-band signals as the low current amplifers used in others. I did not want to have this degradation at this point because these 3 dB loss fully adds to the noise figure and herewith to the sensitivity of the device. The Mode-S Beast much more should be a device mainly designed for sensitiviy. The story tells that only in a few cases strong out-of-band signals disturb reception, so this decision was correct.

	Anyway, in just a few cases there are too strong signals degrading the Beast's performance. From my long-term RF experience I know that an external filter can be made so that the system performance does not degrade. These filters are large, based on a mechanical construction and not able to be integrated onto the PCB, as you see in below photos. But the parameters reached with these filters are really outstanding and worth the effort.

	==The Filters==		==The Filters==

imported>Dl4mea: /* The Filters */

2013-11-14T16:18:54Z

The Filters

← Older revision		Revision as of 16:18, 14 November 2013
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	\|-		\|-
	\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz		\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz
	\|<ins>Technical data:</ins><br>passband attenuation: 1.2 dB<br>-3 dB bandwidth: 8 MHz		\|<ins>Technical data:</ins><br>passband attenuation: 1.2 dB<br>-3 dB bandwidth: 6.4 MHz
	\|}		\|}

imported>Dl4mea: /* The Filters */

2013-11-14T16:18:06Z

The Filters

← Older revision		Revision as of 16:18, 14 November 2013
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	\|-		\|-
	\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz		\|<ins>Technical data:</ins><br>passband attenuation: 0.5 dB<br>-3 dB bandwidth: 13.5 MHz
	\|<ins>Technical data:</ins><br>passband attenuation: 1.5 dB<br>-3 dB bandwidth: 8 MHz~~<br>(to be confirmed with next build)~~		\|<ins>Technical data:</ins><br>passband attenuation: 1.2 dB<br>-3 dB bandwidth: 8 MHz
	\|}		\|}

imported>Dl4mea: /* Measurements of the 3 Pole Filter */

2013-11-14T16:17:08Z

Measurements of the 3 Pole Filter

← Older revision		Revision as of 16:17, 14 November 2013
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	{\| class="wikitable"		{\| class="wikitable"
	\|[[File:3pole-narrow.~~gif~~\|~~800px~~\|The 3 pole passband measured with R&S FSEA30]]		\|[[File:3pole-narrow.jpg\|400px\|The 3 pole passband measured with R&S FSEA30]]
	\|-		\|-
	\|''The 3 pole passband measured with R&S FSEA30''		\|''The 3 pole passband measured with R&S FSEA30''
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	{\| class="wikitable"		{\| class="wikitable"
	\|[[File:3pole-vna-02.jpg\|~~800px~~\|Filter Measurements with a R&S ZVR VNA]]		\|[[File:3pole-vna-02.jpg\|400px\|Filter Measurements with a R&S ZVR VNA]]
			\|[[File:3pole-s11b.jpg\|400px\|S11 and S22 with my own FSEA30 and a directional coupler]]
	\|-		\|-
	\|''Filter Measurements with a R&S ZVR VNA''		\|''Filter Measurements with a R&S ZVR VNA''
	\|}


	~~{\| class="wikitable"~~
	\|''As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good reproduction''		\|''As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good reproduction''
	\|-
	~~\|[[File:3pole-s11b.gif\|800px\|S11 and S22 with my own FSEA30 and a directional coupler]]~~
	\|}		\|}

imported>Dl4mea: /* Measurements of the 3 Pole Filter */

2013-11-14T16:08:08Z

Measurements of the 3 Pole Filter

@@ Line 57: / Line 57: @@
 |-
 |[[File:3pole-s11b.gif|800px|S11 and S22 with my own FSEA30 and a directional coupler]]
 |}

imported>Dl4mea: /* Measurements of the 3 Pole Filter */

2013-11-14T15:19:12Z

Measurements of the 3 Pole Filter

← Older revision		Revision as of 15:19, 14 November 2013
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	~~----~~		{\| class="wikitable"
			\|''As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good reproduction''
	~~[[File:3pole-s11b.gif\|800px~~\|As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good ~~reproductionr~~]]		\|-
			\|[[File:3pole-s11b.gif\|800px\|S11 and S22 with my own FSEA30 and a directional coupler]]
			\|}

imported>Dl4mea: /* Measurements of the 3 Pole Filter */

2013-11-14T15:10:30Z

Measurements of the 3 Pole Filter

← Older revision		Revision as of 15:10, 14 November 2013
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	\|}		\|}

	~~As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good reproduction:~~

	[[File:3pole-s11b.gif\|800px\|S11 and S22 ~~measured~~ with ~~Rohde & Schwarz~~ FSEA30 and a directional coupler]]		----

			[[File:3pole-s11b.gif\|800px\|As an experiment, I also measured the S11 and S22 with my own FSEA30 and a directional coupler, and I got the same values as with the VNA with a very good reproductionr]]

imported>Dl4mea: /* The Filters */

2013-11-14T06:22:47Z

The Filters

← Older revision		Revision as of 06:22, 14 November 2013
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	{\| class="wikitable"		{\| class="wikitable"
	\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|1090 MHz 3 ~~Kreis~~ Filter ]]		\|[[File:1090MHz-3Kreis-Filter-03.jpg\|500px\|1090 MHz 3 Pole Filter ]]
	\|~~picture to be added~~		\|[[File:5pole filter-4-resized.jpg\|500px\|1090 MHz 5 Pole Filter]]
	\|-		\|-
	\|''The 3 pole filter (both ports N female)''		\|''The 3 pole filter (both ports N female)''