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--- guides:radio_modules:ntx2 [2013/06/12 17:45] – created upu
+++ guides:radio_modules:ntx2 [2016/09/05 05:58] (current) – upu
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-===== NTX2 =====
+===== NTX2/NTX2B =====
-The [[http://www.radiometrix.com/|Radiometrix NTX2]] is the main radio transmitter module in use for UK HABing - it is available in 434.075 and 434.650MHz variants. The NTX2 is a 3V Narrowband FM module and primarily chosen for its data input characteristics - which are analogue rather than the more usual digital.  This enables narrow frequency shifts and pulse shaping to be obtained. Output is 10mW. Current draw is 20mA when transmitting and 0.6mA in standby. The input voltage to frequency characteristics of the NTX2 are reasonably linear at around 1.9kHz/V about the 1.5V input centre point - see graph below. The graph shows frequency offset (kHz) against data input voltage over the 0 - 3V range.
+==== Overview ====
+The Radiometrix NTX2/NTX2B is the most popular radio transmitter module in use for UK HABing due to its simple operation and robust construction. The original version was available in 434.075Mhz and 434.650MHz variants. The newer NTX2B is more stabled fitted with a TCXO but Uputronics [[https://store.uputronics.com/index.php?route=product/product&product_id=60&search=ntx2|sell a modified, frequency agile version]].
+==== Details ====
+Default output of the module is 10mW (Radiometrix do a 25mW HP version). Current draw is 20mA when transmitting and 0.6mA in standby. The input voltage to frequency characteristics of the NTX2/NTX2B are reasonably linear at around 1.9kHz/V about the 1.5V input centre point - see graph below. The graph shows frequency offset (kHz) against data input voltage over the 0 - 3V range.
-There is a [[http://ukhas.org.uk/guides:linkingarduinotontx2|guide on linking the NTX2 up to an Arduino here]].
 {{guides:ntx2.jpg|}}
-The reglatory requirements for airborne operation on this frequency are that the channel bandwidth must be less than 25Khz and less that 10mW ERP. There are no duty cycle requirements in this frequency band.
+NTX2 modules can be powered directly from the batteries having its own internal 2.7V regulator. The manufacturers datasheet is here [[http://www.radiometrix.com/content/ntx2|NTX2 Datasheet]]
-The NTX2 temperature stability isn't great - in addition to drift the frequency shift tightens up with decreasing temperature.
+==== Legislative ====
-**NTX2 Adjustments**
+The regulatory requirements for airborne operation in Europe on this frequency are that the channel bandwidth must be less than 25Khz and less that 10mW ERP. There are no duty cycle requirements in this frequency band.
+Use of this module in the United States requires operation under an amateur license.
+==== Frequency Stability ====
+The original NTX2 temperature stability isn't great - in addition to drift the frequency shift tightens up with decreasing temperature. Adequate insulation is recommended, ensuring the module isn't exposed to rapid temperature changes is essential. The newer NTX2B with its TCXO is much more stable.
+==== NTX2 Adjustments ====
 Removing the sticker from the NTX2 package reveals 3 holes in the metal casing - 1 test point (I haven't checked what it is) & 2 adjustments.
@@ Line 18: / Line 30: @@
 The lower adjustment screw seems to be a pot adjusting the [[http://en.wikipedia.org/wiki/Frequency_deviation|deviation]]. With the voltage driven FSK implementation we use, this conveniently allows for fine tuning the shift.
+==== Where to buy the NTX2B ====
+  *[[https://store.uputronics.com/index.php?route=product/product&product_id=60&search=ntx2|Uputronics sell a frequency agile version of the NTX2B]]
+  *[[http://radiometrixstore.com/ntx2b.html|Radiometrix Online Store]] - Only available in 434.075 and 434.650
+==== Other Notes & Further Reading ====
+Radiometrix are understandably unable to offer technical support on these modules when used in high altitude ballooning therefore please direct all technical support queries regarding the operation of these modules to the UKHAS mailing list or preferably the #highaltitude IRC channel.
+There is a guide on [[guides:linkingarduinotontx2|Linking an Arduino to a Radiometrix NTX2 Transmitter]] here.